It’s not confusing, there’s just nothing to gain from it. Federation makes sense for communication like e-mail and social media like Mastodon or Lemmy, where you have a “home” and want to be able to interact with others regardless of their server. But with wikis, it over-complicates things with little gain. Right now, people browse wikis on different websites. You don’t have a “home,” and that works just fine.

What makes a good wiki sustainable is if its articles are under a libre license, and if its database can be downloaded.