It might power 20% of all domains, but that doesn't equate to 20% of mindshare. Individual Facebook pages should be counted individually in this context.

Wordpress also is not really a federated system, because the individual sites are not interconnected.

I want to be very snarky with an unnecessary description of a hyperlink... another day.

Wordpress sites _are_ to a degree a federated protocol beyond hypertext: https://make.wordpress.org/support/user-manual/building-your...

What would it require to make it a federated system? And interconnected?