Audibly encouraging fights among males literally ties into the theory. The hypothesis is that female moaning attracts nearby males, the males want to procreate, but only one male's genetics are going to actually form a child, and it is in the species' best interests for that child to contain the DNA of the most-likely-to-survive and procreate male. It doesn't matter whether the guys all form an orderly queue to some daily gangbang (which was absolutely NOT the case), or start fighting amongst themselves to be the only one with a chance (which includes the possibility that another had ejaculated inside her prior to this) - the purpose of her vocalizing was to encourage males in the area to compete, especially if she's already in the middle of the act. There's enough merit here to suggest further study into the area, especially given that neither of our theories are proven.

You seem to be fixated on an argument I've not made, and I may not have worded it clearly enough. I'm not suggesting that primitive human females started moaning in an attempt to initiate a gangbang because cave-dwelling women were insatiable whores or wherever. I'm suggesting that those vocalizations were a method to incite breeding competition between males in the area, and that this lead to natural selection.