and only split once the userbase of that community has developed enough.

I think that's the key thing. I do quite like the idea of more specific communities (which I've expressed a couple times), but only once there are enough people participating that they won't just sit dormant. Like I agree, tabletop gaming is something I'd very much like to have a dedicated community for, but not right now.

My perspective is that the main value in more niche communities is that they help people find posts related to a specific internet amongst a sea of unrelated posts. E.g. if I want to chat about specifically Citizen Sleeper, but the main gaming is flooded by posts about Elden Ring, other people interested in chatting about Citizen Sleeper might not see my posts.

(On that note... Anyone want to chat about Citizen Sleeper?)

At this point, that's just not an issue Lemmy has. Keeping things more general for now is definitely the right strategy.

And like several people have mentioned, Lemmy is federated! So if someone wants to go ahead and spin out some more niche communities, they are free to do that on their own instance and we'll all still be able to join in!