You’re actually right they are decentralized and your account would continue existing if you had your own PDS and either you or someone else was running a relay.

The OP above is essentially saying what if the relay goes down, but anyone can run a relay it just costs a few hundred a month and there’s little reason to do so (right now).

Usually people on this side of the Fediverse aren’t in the know on the AT Proto inner workings.

One thing you can point out is protocol ownership, Bluesky owns the AT Proto protocol and can change it however they like while ActivityPub is a W3C ownership so a lot more resilient (albeit slower changes)