(this is not an argument to any previous *particular* post)
I think that girls and guitar can be equivalent to something like guy and... ballet. Now how many guys do you think would actually go all out and be good at ballet? Or even consider being a ballerina?
Probably very, very few.
Then suddenly the movie Billy Elliot comes out and there're more guys daring to take up ballet. But you still don't see a significant change in performance yet, as compared to girls.
Now think of guitar and girls. Decades before guitar was like a guy's instrument (especially the electric guitar). Get good, get laid. But with mordernisation more females are picking up the guitar, and this can be proven by the article in the first post of this thread. But you can't expect results in a large scale so quickly.
Don't just generalize if you don't see results. That's all I've got to say. Even if girls aren't meant to play the guitar (-_-) it still doesn't mean that ALL girls are condemned. Nope.
(again, this is not an argument, just my opinion.)