Mastodon has serious UX problems that even other federated networks don't have. I'm pretty well tech literate and love Lemmy, for instance, but I just couldn't ever get Mastodon to stick for me, like it just didn't have the right feel and wasn't fun to use. And if it's not working for me then it's never going to take off with a more general audience.

Bluesky is a lot better. It still has some issues that I feel keep it from fully replacing Twitter, especially Twitter before Elon screwed it up. But it does manage to keep me checking it, even though it's probably only once or twice a week max.