I... can't see anywhere where they are complaining? This was just a post about how much the server cost to run. They updated it over time with new numbers as they beefed up the server capacity. But the post basically says "Here's how much it costs to run, and we have plenty of money". I don't see the complaining?

I mentioned Lemmy on Mastodon and some people noted some controversy surrounding the "main" instances. I don't know exactly what concerned people

One of, if not the most active lemmy instance is a Marxist, pro-Russian war, pro-CCP, pro-North Korea community. When I signed up on lemmy.ml a while back, it was almost all you saw.

The problem with reddit alternatives is that, until now, the only people leaving reddit were the ones kicked off. They needed new homes and they found them in unmoderated communities they could host themselves, like lemmy.

Some of us have been waiting for some time for more "average" redditors to make the move, so this exodus is like Christmas coming early.

80/20 rule.

When you are creating something like Lemmy, where you want wide uptake, you need to pander to the masses.

The /r/selfhosted surveys show around half of self-hosters mostly or exclusively use docker. A significant portion of the rest can use docker if needed.

If you're in the 20% that isn't covered by the most common setup, then it can be frustrating. But supporting that 20% takes as much effort as supporting the other 80% (see 80/20 rule), and when things are new it's just not where the effort should be focused.

So you have all those servers, but why can't you install debian or ubuntu server on one of them?

You could also get a $2/month VPS and run it on that. Beehaw is run on something similar (though apparently $12 a month, but a lot more users).