I think while the general communities have made it, a lot of niche communities failed to attract enough population to keep on generating more content. As an example, just search for the "Imaginary" series of landscape art communities on the Fediverse (eg. ImaginaryVistas). Many of them don't have any recent posts or 1 post per days or weeks. That's not enough to keep people invested. Even the largest digital art community is still mostly carried by 1 person.
As someone who mostly lurks/occasionally comments and someone who likes to view hot/active posts from all communities, repeat posts from similar communities in different instances is something I find really annoying. I'll see the same post four or five times as I scroll. It can make things feel really empty to see the same things more than once.
https://lemmy.ml/c/collapse (the original/direct view of Collapse @ lemmy.ml) shows 2.11k subscribers. I don't know whether this number shows only subscribers from lemmy.ml or an aggregate of all subscribers across the fediverse.
Unfortunately, another issue even if the count on the direct link to the community is an aggregate, is that it's probably not counting people who are stuck in a "subscribe pending" state. A ton of the communities I subscribed to weeks ago still show in this state on my communities page. I understand that what this means is that I'm subscribed on my end so that everything works for me, but the original community hasn't acknowledged my subscription, so I expect that this means it also doesn't count me as a subscriber.
Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: !collapse@lemmy.ml
I think a lot of the imaginary communities were on one of the .ml instances so are currently in suspended animation. That domain shutdown was really badly timed...
Otherwise, it's the standard problem that only a small % actually post and Lemmy is much smaller. I do think that a better/fixed hot algorithm would help with post discoverability for smaller communities though.
( I mod a niche imaginary community for the Cosmere book series(es))
Yeah, I don't think asking communities that are already fairly small on Reddit to create the same community on Lemmy was a good idea.
For something like this it'd be best to start with a single community for the whole broad topic (like, ImaginaryStuff). Hell, Reddit used to be a "single subreddit" originally. And the niche subreddits didn't pop up until fairly recently where they were actually able to entice enough people to use them.