The benefit of federation would be shared accounts. Which aren't at all needed.
Like, you mention fandom. They have more or less killed wikis. They were not the norm a decade ago. And it was pretty common to see the trivia section for an actor or actress say "And they were in star wars!! WOOKIEPEDIA BITCH!" as a link
And that is how the internet worked. That site about engine repair? If they felt there was a good site on how to do timings for a transmission or whatever, they would link to that. And they might even contribute on multiple message boards with multiple accounts.