I don't know, but it could be interesting to try. I could easily imagine topic-focussed servers that go into more depth on specific topics. Perhaps you would only federate things that are at a high level, or directly linked. Kinda like a wiki, but with each community doing it's own decentralised curation and moderation..

I haven't seen any spam on Lemmy yet, and only a tiny amount on mastodon (I'm much more active there).