Well, given you have to give permission (I think), I couldn't find my display name. If it is, that is pretty funny. On the other hand (other than security), I don't care if their username and display name are the same.
But, as you say, it is a security risk. And, given if you Google the top 10, which would be something like, {password, 123, 1234, 111, passwords, letmein, etc.} a script would make it rather easy. While on the subject, so I think it is legit for me to ask this, I am always careful about writing my email address in a forum or anywhere for that matter, like:
badams AT riverviewpediatrics.org_removespam. Are the email addresses that are in form boxes (or whatever) safe from bots?