It’s time to demote Twitter usernames as the canonical @-names online. @davextreme (on both Micro.blog, where we’ve been discussing this issue, and Twitter, where you might be reading this) has some good thoughts in this direction.
@DrOct I'm not actually suggesting using phone number as the ID for point-of-contact (unless you want to), just as the semi-public (as in, you don't care if it's leaked, as you do with an SSN) central coorditing authority that links all of your various accounts and acts as a switch-board between them. It can also potentially be used to confirm that the @-name you're sending a message to is connecting to the person you intend to be connecting with.