Nobody cares about decentralization until they do
A recurring line in discussion of federated, decentralized social media is that no one cares about it. They just want their Twitter without the Nazis.
Which is okay. But how it looks on the backend matters. When the illusion of a unified user experience breaks, how accessible the escape pod is matters.
Consider this scenario: you try to log on to your favorite social media one day and the server you were on is just gone.
Mastodon and the broader ActivityPub (AP) network offer little hope here. Everything lived on that server. There was a popular server in the little subculture I inhabit that was ganged up on by some shitposting instances until the mods quit and it shut down. I can't convince anyone in that subculture to try Mastodon whether for the first time or again. They've all heard about what happened. They know there's a different group of servers that picks random instances to attack similarly.
And every single one, with few exceptions, that tried Bluesky prefers it.