In Steam it is actually the case that a user can select their own display name (distinct from the account name used to log in) and change it at any time (and th

In Steam it is actually the case that a user can select their own display name (distinct from the account name used to log in) and change it at any time (and there's very few restrictions on what you can set it to, the system doesn't care if every single one of your friends has the same display name). This function is separate from the "tagging" feature, which is helpful for keeping track of those friends who frequently change their display names and avatars. It's also possible to view the list of previous display names a given user has had, at least if you're friends with them.