There is guy who repeatedly abuses other player, Says bad stuff that I don't want to say, Quits 1v1 matches before he looses without resigning(has high rating on some of his account like 14xx).
People started to notice him that's why now he created multiple accounts to ruin fun for others. ( I was able to recognize his cause he loves to host and he lags and his talking pattern)
some of his accounts are nothing29xxx(somthing) and whateverman
My suggestion:- require at least email address