This seems strictly better than what we have, though, where Twitter or Facebook decide the same. At least you can move instances, or start your own. EDIT: also

This seems strictly better than what we have, though, where Twitter or Facebook decide the same. At least you can move instances, or start your own. EDIT: also to note, email does kind of work this way with administrator applied spam lists. I would not want to use an email service that couldn't or wouldn't filter spam.