@Mrfunkedude not all of the fediverse using ActivityPub. Some federated services, like Diaspora chose not to. They are still federated, and it is still possible to interact with such users in some cases. (i.e. say both you and someasshole@diaspora.instance) are both friends with friend@friendica.instiance since their friendica instance supports both ActivityPub and Diaspora on thread of friend you can talk to someasshole as Friendica will send to both of you but Mastodon won't let you follow them because they can't see anything someassholes posts natively.