I don't think it's a matter of sex, but rather a matter of work. I don't think I've ever met female player with the drive to not only enjoy the game, but to achieve the level of system comprehension and put in the extensive work required to DM, at least without a lot of assistance.
My wife has DM'd solo games for me a few times, and we had a lot of fun, but when I'm the one who knows all the rules, it ends up with me as the GM, but I'm running characters and she's playing the encounters.
Now, that's not to point out women I've met as being poor players, but rather that there are fewer women I've met that want to devote the time and effort to the system than there are men I've met. But then, players of both sexes tend to be a bunch of lazy scum anyways. :P
Anecdotal evidence of course, but I sort of agree and sort of think you're completely wrong.
Most of the female GMs I've played with (and players too, but to a lesser extent) have been less interested in system mastery and extensive rules knowledge than some of the male GMs. That's not an matter of drive or hard work in my experience, just of a different focus. An awful lot of hard work can go into the campaign and adventure design and that has to be done for every game, not just a matter of getting the rules down once.
The female GMs I've played with generally favored more rules light systems over things like D&D/PF anyway. As, in general, do I.