By “gatekeepers” I mean something like this: it’s usually easier for women to get casual sex if they want it than for men to do so. Men are usually more motivated to increase their N count than women are. Men have to initiate, escalate, and pursue more than women do. Women may receive offers of casual sex, but turn them down; men would accept the offer, but never get one. Men are often "orbiters" in friendships where they want sex and the woman doesn't.

An example of this issue is the study by Clark and Hatfield, where men usually accepted offers of casual sex and women declined:

https://www.psychologyinaction.org/psychology-in-action-1/2012/01/03/casual-sex-are-men-and-women-so-different

I have heard of (or read about) the following explanations for this phenomenon. Can you either support or shoot down any of these explanations, and/or give your own explanations?

(1) Men are overall bad at pleasing women sexually or don’t care whether women orgasm, so women are less motivated to seek out sex.

(2) Men are more violent, causing women to fear going home with a strange man.

(3) Men are biased against women with high N count.

(4) Women are biased against other women with high N count.

(5) Women have a lower sex drive.

(6) Women are worried about the possibility of getting pregnant.

You could also disagree with the premise and say that women are not "gatekeepers."