Gregory's Server
On WordPress.com, you need a business level account, which is quite expensive, before you can install plugins.
But now you can just use an admin option to federate, without a plugin. I did it recently, quite easy.
Maybe that's why so few are using the plugin.
@EricLawton Yes, as you note, WordPress.com already has the same functionality built-in. No need for the plugin.
There are millions and millions of other WordPress servers out there, though, and *they* are the target for the plugin.