The splintering is an issue I’ve run into already. When I searched for squaredcircle on the assumption the subreddit community had started moving, I got results for five ‘squaredcircle’ communities across five different instances and none of them have a significant membership.
Yeah, I blame Lemmy’s fairly terrible cross-instance community discovery and just being young. Reddit had overlapping communities as well (tons of DnD subreddits, tons of aiti subreddits, and there were plenty of high-profile community split events over mod policies). But because it was so well established in recent years… most communities had standardized on one well-run subreddit.
But Lemmy’s community search is so poor, I think folks legit fail to find bigger/better off-instance communities and so no single one gets a toe-hold to gain critical-mass… they all just kind of smoulder with catching fire. Hopefully better community discovery will come and the well-run communities start to rise to the top.