Two of the three pillars highlighted on the atproto.com homepage – portable accounts, and algorithmic choice – would require significant retrofitting counter to ActivityPub server customs to achieve.
(And the third, "federated social", is arguably an area that at-proto is erring by staying too close to the ActivityPub approach. We know what happens to 'federated' systems under network-economics: they trend toward semi-feudalism.)
But the fediverse doesn't use any algorithms, it just shows you what/who you subscribe to. This is the way social media should be. If I don't want to see something or someone I can just block them.
It's only gone downhill since the sites started adding algorithmic crap and filtering things out to increase 'engagement'. This made facebook totally useless for me to keep in touch with my friends.
Portable accounts are indeed important and a big thing missing from ActivityPub, I agree there.
But I'm completely over to IM now to keep in touch with friends. Social Media has invalidated its own usecase for me.
