In the fediverse, I think it really come down to which Named communities can grow the most in the near future; people go where other people are, so the easily accessible names and largest communities are going to see the easiest adoption by new users interested in that topic.

There’s been a fair bit of discussion on how to implement “multireddits” in Kbin and Lemmy (Lemmy issue, Kbin issue) and depending how that shakes out it might make even that less of a problem. I could group all those MLP groups together and view them all as a unified interface.