Kevin and Ryan raise some very good points about where OStatus went wrong. I absolutely agree that Webfinger is a terrible approach to identity brokering (and I have a lot of problems with the
/.well-known thing in general), and while I haven’t looked seriously into Salmon because it seemed unnecessary, it also sounds like it was a major pain in the butt to deal with on top of that.
What’s frustrating to me is that Mastodon (and possibly ActivityPub itself?) makes Webfinger absolutely necessary to support (and provides worse feed discovery/modeling as a result!), and I believe it does something Salmon-esque for conversational threading as well (although I’m sure someone will correct me on this point).
Meanwhile, another reason to avoid ActivityPub is that things like this are necessary.