The post was meant to be a concise description of an architecture, and is not meant to be comprehensive in any sense. I definitely agree that diaspora, and a few other projects out there feel like they should be a part of it and in fact, it started out as a more extensive post including a roundup, and a motivation on the state of social networks. Hopefully, it is the first of a few written works (as well as technical works) and there is plenty to be said about the topic.