@trwnh linking, which as you point out is key – to people – depends on regular people being able to share their names. I learned a long time ago that most people aren't good at groking the HTTP part of links, because the structure of links is actually really complex. When you mention xmpp and email, the identifier is the thing that makes both of those networks work.
For me, "fedi" or "AP" or the social web or whatever we want to call it has always been about making personal identity linkable.
@trwnh when the first round of "social networks" were built, the first thing that got added to the databases were a "users" and a "friends" table, because "the web" doesn't (didn't?) have that.
Decentralizing that is a radical act, and the sorts of things that we can do with a linked [bi-directional] web of people is infinite and bounded only by our imaginations. AS and AP actions and data formats and C2S are, as I think you're saying, just stubs for rebuilding the old world in a new way. ❤️