Well, it does check the IP and email. Part of it is ignorance, the other is people who think it is cute to have a display of "mayibyourfootdr" not realizing that when I go to help him configure his router, it is courteous to say Hi mayibyourfootdr. Given their name in their profile, I am tempted to just change it. I will say that a gentle nudge in a post will get them to change their username.
Generally, while you say it is confusing for them when making their profile, it is doubly difficult to understand the difference between a display and a username.
