It doesnt have to be a federated “wikipedia” it can be a federated wiki. Look at the fandom controversy right now where a bunch of games are now moving to their own wikis. A federated wiki software would let all those game wiki host their own wikis but still contribute to eachother without making an account on each wiki.
I want to subscribe to the minecraft and the terraria wikis from my garrys mod wiki account to get notifications on new pages and i want to contribute to them without making an account on each. Federated wikis would be cool
Also i DEFINITELY want a full fledged wiki page available on lemmy so each community can have a wiki with multiple pages and nice linking and a WYSISWYG editor like wikipedia