That's strange, not long ago I was thinkig about that paradox too. I really didn't see any girl for I could say "She kicks ass" or something.
All girls sorry about that :p, but I think they are little stupid for that, and they mostly have weak fingers, but the guitar requires "little" more than that. There are some "actions" reserved for man, playing guitar is one of them.
They are better singers than guitarists (mmm....Candice Night :))