Agree, the pair username, password can be invalid for 2 reasons: It is the intended user, but the password is wrong It is the right password, but the user is

Agree, the pair username, password can be invalid for 2 reasons: It is the intended user, but the password is wrong It is the right password, but the user is mistyped The login screen has no way to know when is one or the other. The OP wrote a whole article based on the wrong assumption, and since the title is a click bait, it made it to the front page of hacker news. Sad.