@0x1C3B00DA That's only one of two options. The other one is that you can use a nomadic identity with different servers, so that those can still be focused on a specific thing, but you can use the same account to post to say a micro-blogging network as well as photo community, or some Lanyrd-style event calendar site. All of them need moderation, and I also wouldn't want to lock people's entire social life into one server that they probably signed up for on a whim.
@0x1C3B00DA Also, "has held back" is a bit of a strange argument, considering that ActivityPub is not even half a year old and we have all these implementations working and being used already. Even if it's not a generic AP server, it certainly has done more for AP adoption than any other software, being the first implementation at all really.
@0x1C3B00DA ActivityStreams standardizes the general format, but not the actual post types etc. There's https://www.w3.org/TR/activitystreams-vocabulary/#object-types but it doesn't contain a good match for microblog posts. They're neither articles nor notes. Problem with these specs is that a lot of the content comes from theory, not implementing software. Hence, they cannot cover real-world usage very well.