As with every other "Name the great ___" quiz on this site, this is not intended to be an exhaustive list. A quiz listing every great guitar player would take hours. So not every guitar player is here, and maybe not even your personal favorite (how dare the quizmaker put this quiz together without consulting you!).
The quiz is fine as it is. Every name on here is a famous and influential guitar player. There are guys with killer chops, and there are guys like Cobain and Townshend who were hugely influential, if not renowned for their technique. They're all great. Not everyone needs Eddie Van Halen's technique to be great. There is a guy in every town in America that can tear through the solo to Freebird, but how many people wrote Nevermind? We're all proud of you for knowing who Joe Satriani is (and Robert Johnson, the patron saint of guitar know-it-alls). Now get over yourselves.
Maybe not best known for guitar but they played, and they are legendary.