There is a known strategy called EEE (Embrace, extend, and extinguish).

First, they embrace the open web. Millions of people who never would've joined the Fediverse (and, probably, don't even know what the Fediverse is) flock to Threads and start to interact with us.

Then, they extend the open web, adding features to Threads that aren't compatible with our servers. People on Threads don't understand what's wrong with our server (even though it's Threads that's the source of incompatibility).

Finally, they decide they're "having trouble maintaining compatibility with third party servers" and start to break off from us, leaving us with no way to interact with our new friends. Unless, of course, we make a free Threads account...

Google Talk is perhaps the most relevant example of this. Here's more details.

Great answers in general, but I just want to pitch in my answer, because this was how I was able to make it click, and maybe it'll help someone else

Let's imagine if a company wants to destroy a small group. In this case, Meta likely wants to destroy the Fediverse because it recognizes that the Fediverse could compete with Meta in the future. What can that company do? If you were that company, this is what you can do:

1. First, pretend to be nice and say that you want to work together with that group. You want a cooperation, and as a big company, you have the resources to make the group even better. The small group is ecstatic and accepts the cooperation.

2. At first, you do exactly what you said you would do. You put in 50% (or sometimes even more) of the effort, and the developers of the small group put in 50% of the effort. The cooperation seems pretty good and lots of work is getting done.

3. Over time, you slowly start putting in less and less work into cooperating. Maybe for one feature, you put in 40% of the work, then for the next, you put 30%, etc. Eventually, you're developing your own features without sharing your work with the devs of the small group, and the devs have to struggle to try to figure out what you did. Meanwhile, the devs still think you're acting in good faith, so they're still sharing their side of the work.

4. Users look at your platform and the small group's platform, and they think that the devs of the small group are just not really that competent. They don't realize that the reason why the small group seems to be lagging behind is because you're refusing to share your side of the work. Users start switching over to using your platform, since it's so the same content anyways, right? It's just less buggy and has more competent development, right?

5. Once most of the users have switched over, you then suddenly flip your stance and say that, really, cooperation isn't really working and that you want to stop cooperating. You break off from the small group, and since most of the users have already switched over to your platform, they leave your small group, not realizing that they've been duped. The sudden decrease in users in the small group completely devastates the group and the group never fully recovers.

The group could still exist after the break, but its reputation has been destroyed and people no longer see it as a viable alternative to big companies. As a result, even if the group remains standing, the user base will not grow any longer, and the group may even end up with fewer users than they started with.

How do we know for sure that what I said will happen? Because other tech companies have done this exact same thing before. In fact, it's so common that it's got its own name: EEE. So a lot of people here are seeing the writing in the wall. If Meta is offering a cooperation with the Fediverse, what do you think is the likelihood that they're actually wanting to cooperate in good faith?

The old Tripple E is the problem...

Meta come in with open arms embracing ActivityPub. They use our established communities to supplement their own content, and draw in users that would never have heard of this place to sign up to Threads.

All's going great. But over time they start extending what Threads can do past what ActivityPub can. This "accidentally" starts causing incompatibilities with ActivityPub, which could already cause some users to migrate to Threads.

Once they've done this enough, they use their generated incompatibilities as an excuse to defederate from the Fediverse. This forces anybody on this side that still wants to interact with the friends and content they've made through Threads to sign up over there leading to an exodus.

If that exodus is big enough, it could be enough to extinguish the Fediverse completely. Meta wins, we lose.

Even if there is nothing wrong with Meta trying to federate with the Fediverse, I do not want them here.

Honestly, at this point I am quite jaded and sick of the shenanigans of big tech. Repeatedly they have violated the trust of their users. Unless they show active change in the way they conduct their operations for the benefit of the end user and not advertising agencies, I would prefer to not have them in my life if I can help it.

EDIT:

I might have misread the intention of your post. If you are asking about the fallout of Meta federating, there is a possibility that they attract too many users to their platform. This is my personal anecdote. I wanted to get rid of all products owned by Facebook to the point where I told my contacts that I am switching to Signal and will be uninstalling Whatsapp. I even reasoned with them that I wanted to choose not to use Whatsapp, and that I still wanted to communicate with them, albeit on Signal. I even emphasised that I wasn't asking them to uninstall Whatsapp. Ultimately, only about a third of my contacts joined Signal.

Everyone says there is a choice in not using Whatsapp, but is it really a choice when there is no one to talk to on Signal? That is my worry that something similar would happen with Threads.

@Cevilia@Lemmy.blahaj.zone has the most correct answer I think but I want to add my opinion as a refugee.

Right now newer Fediverse users like myself are experiencing a new level of choice and autonomy that we didn’t get with the other centralised services. EEE is a practice that slowly erodes that freedom by diluting our user base and eventually forcibly absorbing it.

An analogy:

The centralised services (Reddit, Facebook, etc) are a city and we used to be citizens. However, we took exception to how the city was being run and protested. In response, we were told ‘tough luck, like it or leave’, so we left and are now outside the city walls.

We enjoyed a lot of what the city provided so we’ve started our own village and built the tools so that other people can start their own village too, all in the hopes that this collection of villages will eventually function like the city but without the small group of councillors who were in charge of everything.

Now the councillors are peering over the city walls, seeing that we’ve got some basic services set up and are starting to attract more villagers and that means the stuff we’re making is pretty cool. So they’re expanding their city wall to a point that’s right next to our village and telling their citizens to visit us to look at our cool stuff, and will say that it is actually the city providing the cool stuff because they were generous enough to allow the citizens through a gate. Eventually they’ll try to expand the wall around our village too and the citizens will like this so too few people will say anything about it.

Now we could just move again and start a new village, but should we have to? Why would we bother when we can just put up a magic invisible wall of our own that stops the city seeing our cool stuff, but still allows the citizens to move to the countryside with us and become villagers.

I think the primary fear seems to be giving Meta access to our user data. The concerns seem to be not completely founded but even then there is still the uneasy feeling with helping facebook of all companies with their next project

As early adopters, many people in the early fediverse had larger sway in the direction that things went. Even now, we have a head start on changing and updating things, adding features, and making improvements to make interaction easier. Many of these decisions are being made for the mutual benefit of the users and ourselves. Large corporations do not think like this as they are driven by gaining users and then exploiting those users for profit. This means we could be seeing injected advertisements and exploitation of user data and content.

Apart from what others have said, just consider the types of people that would join these platforms. While I would encourage anyone to join the fediverse, just think about the low quality of content and thought that the general user on reddit contributes and yet how much more reddit users thought of themselves compared to the cesspools of facebook and instagram users which carry even lower quality discussion. The quality on lemmy now is several times that of Reddit before we made the leap, while the quality on reddit has plummeted. The types of users who would boot lick or care more about their personal inconvenience in the short term over long term prospects and quality are the ones not yet on this platform. Anything linked to Meta is bound to bring a higher proportion of those types of users, as Meta is bound to try and convert their own userbase as well as gather those from twitter and other platforms.

In addition to EEE danger, there are privacy/monetizatiob concerns that others highlighted in another thread (sorry the link is weird, not sure the right way to do it yet) https://kbin.social/m/fediverse@lemmy.world/t/145063/Threads-Monetization-Fears

Besides the whole "Meta being skeevy" thing, the type of people they bring are not people who you want to federate with.

Thank you for asking this. I'm off the same mindset as you and thought Threads and Bluesky joining the Fediverse would be a benefit, not a con. I'll be monitoring replies...

I think what some are saying about triple E may make sense, but closing the door is not a solution, the fedivers will grow and that will attract companies, they can be large and obvious as Meta, or they can grow within the fedivers, but they will arrive and try to take over the place, because that is what companies do. If our system is not strong enough to resist this when the company is as obvious as this, what will we do when a new google '05 is born? It's a challenge, but one you have to go through

The problem that I see at least is moderation, from what I've seen from screenshots and stuff from over there, there are a lot of bad people over there, and many of us at least joined the fediverse to get away from toxicity and people like that.