That might be because many of the men in the industry take various drugs to help with their erections and not cumming too quick. I was friends with several porn stars (both male and female) and was informed that this was the case all the way from the 70s through 2004 (when I was a journalist for a internet porn site).

Also the women make much more as actors. Male actors make very little for each shoot. The only ones who become financially successful are the ones who get into producing their own films. The women also get to make much money on the erotic dance club circuit. I remember seeing Terri Weigel near Springfield MA in the 90s. She was charging $40 just to have a picture taken with her way back then.