(I rewrote the title seven times, I'm just going with this)
I tried Bluesky because of its growing popularity, and I'm confused about its supposedly decentralized nature. Yes, you can "own" your account with a custom domain, but everything else is centralized onto the one instance which is Bluesky - there's no federation or anything like that (?) so I don't see why people promote it as being anti-big corporation even though it may become that at this rate.
With Mastodon/ActivityPub, federated instances connect through the underlying software that they all share. Heck, you can even communicate with other software like Lemmy through the ActivityPub protocol. Sure, I guess you don't "own" your account/likes/etc, but I think it's way better than being locked in to solely one instance and not having the ability to switch if the one your using doesn't appeal to you in some way.
I'm sure I'm missing and/or an incorrect on some information about all this, so I'm really just hoping someone can explain it in a way that I understand.
Personal data storage can be decentralized, although that's missing the social part of the social network.
Identities are set up through a centralized system that in theory they could change, but I wouldn't bet on it.
Relays supposedly can be decentralized, but need to handle all data on the network. So they require massive hosting costs that keep going up as more people use bluesky. Only large corporations can likely afford to run them, and that hasn't happened yet.