Feminists insist that it is about power and violence, not sex. That some of the men cannot even "perform" during the assault.
Certainly there are cases like that, though I couldn't say whether it's most or few. Some, though, are the result of a horny guy who won't take "no" for an answer. Still, it all comes down to force, though the subject of this particular form of force is sexual.
One wonders how the feminists feel about statutory rape perpetrated by a woman? (A few teachers come to mind) Is that sexual assault all about power over and violence towards women? I'm sure many would sincerely claim it was the minor boy's fault.