> I think Steam is an easy example of a service which does it right: Many people (usually in different social circles) can use the same name, you can change your display name easily, other people can see some previously-used names, and you can assign custom names to friends to avoid confusion.
On the other hand, they won't let you change your login name, which would hint that they're using it as a unique identifier of some kind internally, which seems like a bit of an antipattern.
While I would like to change my login name, the important thing is that it's not used anywhere else. This means it does not get in the way of my self-expression, and also that nobody who I talk to through the system can harass me by repeatedly entering wrong passwords.
Come to think of it, that also serves as a counterexample to one of the article's pieces of advice: using an email address as the users login. Steam used to work that way, which is why I have to log in using a string which is an email address I don't use anymore.
On the other hand, they won't let you change your login name, which would hint that they're using it as a unique identifier of some kind internally, which seems like a bit of an antipattern.