I think federation and decentralization work well for email and text-messaging platforms like XMPP and Matrix because those platforms inherently benefit from being decentralized. They work almost seamlessly with federation.

Forums, on the other hand, don’t really need a federated system. Just look at Lemmy and how many communities defederate from one another because of ideological disagreements. When there’s that much defederation, the entire concept starts to feel pointless. Suddenly, you can’t use your account across “Lemmy” because several instances have decided they don’t like each other anymore.

If this much fragmentation is going to happen naturally, how is federation supposed to be the sustainable future of forums?

I think this is a fair criticism of federated forums. You don’t see this same level of fragmentation with email or text messaging.

Centralized but well-moderated forums are what really matter. Federation doesn’t protect good or useful speech, quality moderation does. And by its nature, Lemmy lacks that.

EDIT: There may have been a misunderstanding on my part on what defederation exactly means in the context of Lemmy