is decentralized
It’s not.
I assume someone else can just create a server and join the network of BlueSky?
They can’t.
in reality at the moment its controlled by only one big company.
…yep.
My hope is that they will one day cooperate with Fediverse.
ActivityPub existed before BlueSky did and they chose to make their own, incompatible thing. So I don’t have high hopes for this.
This is what I don’t understand, why would anyone choose to host when there is zero advantage? I sort of feel is by design so they can claim “decentralized” while still having full control over the data.