It’s valuable for .ml to have duplicates since certain instances and numerous individuals are defederated from them. There are also people who are trying to diversify the fediverse by moving communities off .world. Big, opinionated communities like the different news communities are going to spawn new versions as people disagree with mod decisions or the background culture and feel they can’t have the conversations they want.

Some splitting is inevitable, imo, and healthy, though whether it’s good in this or that particular case is a useful conversation to have. Merging communities is also useful, but only when it makes sense (one is barely moderated or barely used, or people have defederated from an instance one is on because of spam, etc.)

I think it’s a case by case basis type situation.