If Matt wasn't so fixated on WPEngine, he could actually do something important and radical by pushing Tumblr as a true user-controlled (i.e. each user has their own TLD) alternative to Twitter, BlueSky, Instagram, Threads, etc.
It gives control to the node operator. You join a node on the basis that you like the operator and trust them to federate responsibly. The end user is along for the ride with the node operator.
That's not how it works in the case of WordPress though, in this case it's not posting to some account on someone else's instance, each blog is it's own ActivityPub instance (as they just add support for the ActivityPub endpoints to the existing hosting)
Mastodon suffers from the same problem Reddit does. Moderators have too much power.
A truly P2P system where the end user has 100% control over what is blocked, and furthermore where they can't be shut out in the cold by capricious mods, would be the ideal social media vehicle.
You can already control who and what you see by running your own server. If you choose to use someone else's infrastructure, don't act surprised when you're subject to their rules.
You sound much better informed on the technical/plumbing details than I. Mainly I was trying to emphasize that the lock-in and high-switching cost from social networks comes from centralized control of the urls. If each content creator controlled their own domain, the discovery mechanism/feed could be separate.
SOLID or ActivityPods, on the other hand...