That’s part of the fediverse. It will be a obstacle for communities that will keep them from getting Reddit sized but decentralized means they aren’t supposed to get too big. I think the best compromise would be allowing you to create multi-communities on the front end or in the client.
But end users may not want to federate with Lemmy.world or Lemmy.ml or overzealous moderators may ban a user on one instance and for that reason I’m not in favor of consolidating communities. I’d rather both grow organically