So what are developers supposed to do with it? is this an invitation to create a compatible network (like email or the web) with different browsers/clients? If so - how is this different from calling electronic mail (smtp & imap) "email" or internet chat (xmpp) "Jabber". To me it looks like we have a new smtp or xmpp but have no "name" for it. ActivityPub might as well be "ACP".