Many communities exist, but mostly on paper.

What I haven't found yet is something substantial and informative like /r/askhistorians.

Individual game subs. Even a niche game usually had just enough of an active community that I could talk about it get help with pretty much anything.

The generic "Gaming" and "PC gaming" and even "BoardGames" crowd is here; but they're mostly good for general news, not discussion of specific games. If I want discussion about lore in Baldi's Basics, for example, I ain't getting it in the general communities.

Transphobia free content is what I miss most. Ever since the reddit influx, there's been a huge rise in transphobia

Communities for people with rare disorders or illnesses. And plant communities for specific plant groups, so not plants in general. But most of all, i miss the fact that i could search for very specific content to see what creative ideas other people had on how to do certain things. Or people who shared many years of experience and experimenting.

r/WritingPrompts. The !writingprompts@lemmy.ml community here only has a few posts.

I think in general we just need more people.. There are communities that exist in Lemmy which are basically empty / inactive that used to be active in Reddit (i.e. Datatabases, Postgresql, FreeBSD subreddits). Perhaps as more people discover Lemmy those smaller / niche communities will see more traffic.

Certain informative, niche communities like /r/neovim, /r/prequelmemes, and er, um /r/sex. I know there are comparable communities here, but the volume is missing. OTOH, everyone is much friendlier here. And, a smaller user base means our comments don't get buried among thousands. Also, I'm really enjoying new-to-me communities /c/risa.

I miss having large and active subreddits for the sports teams I follow. They were my primary source of news for the teams and games at threads were great.

Centralized tv show discussions with episode discussion threads. That hasn’t happened yet :/

I miss communities that I can ask a question to. When I have a problem with a plant, or a legal issue in Japan, or a question about bike brakes... It's nice to have someone to talk to about it that knows more than I do.

Tears of the kingdom content. Gimme those ridiculous builds

A lot of country- or city-specific subreddits either aren't on here or are quite inactive. To be honest they were mostly cesspits on Reddit so maybe it's no bad thing but you occasionally found useful information there.

Other than that, there were a few subreddits that were good for recipe ideas, like /r/EatCheapAndHealthy. /r/ZeroWaste was good too, on occasion.

In general, non-tech related communities don't seem to have migrated over as much. Most of the subreddits I followed were related to technology in some way and now have pretty active communities on Lemmy.

I miss the idea of /r/outside. A kind of role play in a fun , not too abstract context.

Communities for specific consoles, like r/PS3, r/3DS, r/Vita, very helpful for keeping up to date with new plugins and stuff

The ones here either don’t exist, or do but isn’t active at all

I mostly miss my niche subreddits. If the subreddit only has 20-30 active users, that means 1-2 people hopped to Lemmy who might be interested in it.

Doesn't seem like there are many economy/financial/stock focused communities here yet

I don’t miss the exact opposite of a question being posted about five minutes after the preceding post

surreal memes

The sad, basically abandoned subs for tv shows that I never got around to until after they were canceled (shout out to Hello Tomorrow).

Some of the more niche support communities for various reasons, the ones that really only had a dozen or so regs. I hope they’ve found something equivalent to do on the toilet at work.

In Terms of subreddits I haven't found bikinibottomtwitter yet, can't even tell if it exists because the search is broken on every android client and the desktop version too.

Legaladvice, askdocs, hiphopheads, and all the covid care communities like masks4all, crboxes, longcovid subreddit

I don't watch youtube. My inline video contents mostly come from R... Vow, I miss those; they have some really interesting videos I keep forwarding to people.

I'm not sure if it's content or just functionality. I really would like lemmy to be more Google-able than it currently is as I still don't have a replacement for " reddit" like I did with, well, Reddit.

Also, something that will probably take a lot longer is generating content for older/dead topics. For example, my wife and I are watching The Sopranos for the first time, and I used to love being able to search for old discussion threads on each episode. Since Lemmy is much newer, discussions about these kinds of things may never happen at all unless I create a thread, and even if I do, it's unlikely that it'll see much discussion as it's no longer relevant or interesting, especially as you get into more niche interests and topics.

I miss r/conspiracy. The more crazy and outlandish the conspiracy, the more they believed it was real. Interesting people watching but also entertaining to mess with.

Edit: I think they had a convention. The mere existence I found amusing.

Edit2: Shit like:

"We should create the Tax Riot Party, and not pay taxes, and then when they come after us for not paying taxes, we sue the government on the basis of immorality, and then demand direct democracy where we get to allocate our tax dollars into the government programs that we see fit."

Virtual Reality and related subs are pretty small/nonexistent here still.

/r/2007scape, /r/asoiaf, /r/berserk, /r/fibromyalgia, also my big unix multireddit!

r/sweden r/swedishproxlems r/koroa r/livinginkorea r/twoxchromosomes

I miss the bonsai sub and maybe the gunpla one too. I'm sure there's others, but those two were a big part of my enjoying the other site.