the centralized ownership and domain allows for easy community growth vs fragmentation of fediverse. /r/ had that community niche for a while until the mass exodus. sure there are ones that remain, but they have to find roots elsewhere eventually so I'd say dig in and try. if not lemmy then where? if user base is important then lemmy isn't the answer. that's more Mastodon for fediverse.
i don't post much here but I do comment and get ok interaction levels. sure lower than reddit but every community there was vastly larger.