#ActivityPub is the default social networking protocol because we took the time to standardise it at the W3C.
You don't have to be part of the W3C to build on top of ActivityPub. You can make extensions and new applications without ever dealing with a formalised standards organisation.
But the benefit of having the W3C behind us is crystal clear. There have been dozens of distributed social networks, and none has gotten as much traction as AP and AS2.
