This is one of those things where I say, "Oh, I'll ask Fedi, they know."

How much shade should I be throwing at an organization who, when confronted with a potentially ambiguous sign-on (user name only, without domain), chooses the first name on the list of ambiguities and then proceeds to try and do a sign-on, with predictably disastrous results, rather than the sensible thing of throwing an error that says "Sorry, there's more than one of your username, please specify which one you are."?