I have to agree with the parent here... There are other ways to add security, and having an obscure error message doesn't really improve things by as much as the error message can cause real users to go down the wrong path.
Who are you "agreeing" with? Neither me nor the article is arguing for inexact error messages. We both agree that registration pages leaking that information make hiding if a username is correct a pointless exercise.
On that point me and the article are in complete agreement.
