2020-01-20 UTC
# 
[dmitshur] e.g., if a user claims to be "example.com" and example has rel=me link to github.com/example, and the user can sign in to GitHub as "example", then you can be sure they are "example.com" even if github.com/example doesn't link back to example.com. after all, if they can sign in to GitHub as that user, they can edit their profile's website URL field. ah, I guess I'm relying on that assumption which may not be true in the general case.