It depends. Defederation for good reasons is good, defederation for bad or false reasons is generally bad.
As an example, having a strict and democratic defederation/federation policy has contributed to Hexbear having the most active trans community on Lemmy, and it’s a good thing that there’s an actively protected trans space free from bigotry.
At the same time, defederating from instances for political reasons under the guise of other reasons is generally a bad thing.
It’s largely context dependent.
I mean, “bad” in this case is completely subjective. There are large trans communities on other instances (blahaj being the most obvious one) and they have their reasons for defederating from Hexbear.
Hexbear defederated from blahaj, not the other way around. Either way, Hexbear remains the most active trans community on Lemmy.
I understand why anticommunist instances like Lemmy.world defederate from Hexbear, I just don’t think it will help Lemmy.world in the long run, as Lemmy itself by nature is going to attract Communists due to its structure.
I dunno, I feel like anyone drawn to Lemmy for that reason will find lemmy.ml nearly as easily. If world suffers because of bad practices, well, that’s the way it goes. At least the fediverse lives on.
Honestly .world should have just blocked the most common shiposting Hexbear comms like chapotraphouse and dunk_tank as these are what most users found annoying. And I believe ther are more leftists on .world than one might think. There’s a great games comm on Hexbear too, and downvote away on the leftist game posts - Hexbear doesn’t have downvotes anyway!