[hoidofyolen]

the issue is that this is a little myopic when thinking about identity. Your instance server in ActivityPub holds your identity, so when you change servers by mirroring or whatever method, you're giving up your old identity and taking on a copy. That identity part is crucial because if you want to, for example, do OAuth with ActivityPub, your old server technically owns an identity of yours that's just as valid as your new one. It's better on atproto because your identity is always your own (with the caveat that it's currently managed by Bluesky's https://plc.directory, but like they've said, they're working to move this outside the company). ActivityPub will never give you true account portability unless they do something like atproto and allow identity portability. Atproto allows this already. You can move your PDS (where your data is hosted, and the thing that controls access to OAuth) to a new one whenever you want.