Message Boards are fundamentally different and I don’t see a lot of value in federating them considering the big message board platform (phpBB) has 25 years of development and is GPL.

Message Boards are more elaborate versions of subreddits/communities. In all of those instances there is still a single entity that has “all the power in the forum”. You can join another lemmy server, but the admin of that community is still the admin, and the entity controlling the server that community is on likewise, controls the community.

I guess you could have a universal account that could be used across different message boards, but Personally I’d hate that.