E-mail, although it has different clients, is still fundamentally the same thing — you send a message with a subject, body and attachments. However, it seems that social networks built on ActivityPub are fundamentally different — Mastodon is an imitation of Twitter, with short low-effort posts, Friendica is an imitation of Facebook, then there are ways to link blogs… So what I don't understand is, how does this all work together when the formats are completely different?