Mastodon has this. SSB doesn't, because your identity is just your message chain and key pair on your computer.
See https://medium.com/@jimpjorps/a-non-computer-persons-guide-t...
Have I misunderstood how this works?
IIRC, you get a warning if you try to interact with someone who has moved.
I don't want no one to tell me what to do and to prevent that I've got to prevent people from having leverage with me.