To the end of the fediverse, perhaps I sound bitter, "they didn't adopt ActivityPub the way *I* saw it!"
The truth is that Mastodon didn't, but Mastodon also saved ActivityPub. It then painted a vision of the future that wasn't, at least, what Jessica Tallon and I expected of it. But it saved AP.
The fediverse and Bluesky, at great effort, could learn a lot from each other in the immediate term.
In the longer term, neither is implementing the ocap vision I think is critical for the big vision, and in a way, I think maybe neither can be easily rearchitected to achieve it. Well, not yet.