Not every gender or sex-based concept can be or has been studied empirically. Let's say person A complains about the unscientific notion of, "It's okay for women to do x, but men can't do x without getting criticized!" They're talking out their ass, of course. And let's say person B disagrees with them--they're also talking out their ass, so long as there's no actual data proving one person right. Chances are person A has probably interacted with a handful of people who proved their point right, and person B has probably interacted with a handful of people who proved their point right.

Someone who goes to parties a lot and sees their friends or themselves get into one-night stands might tell stories that seem super unrealistic and unbelievable to somebody who only went to a few house parties in college. I could detail some of the shittier parts of my previous relationships, where I was emotionally abused by women, and a woman who's been abused by men might tell me I'm just making shit up, because her handful of life experiences is both A) very painful and B) the opposite of my experience, so she'll feel justified in saying, "oh, would someone please think of the poor men? xoxo."

People naturally just think their own experiences, their own locations and friends/SO's, are universal. It seems idiotic to have three or four bad interactions with a class of people and extrapolate that to x billion individuals, but I rarely meet people who don't do that. If a guy says, "women these days are extremely picky" and he's a 5'2 Indian guy living in a racist town in Alabama USA, well no fucking wonder he thinks that! And it's no wonder someone who responds to him saying "no they're not, you probably just have an unattractive personality" might be someone in a much better location/overall situation.

"Wow, you discovered people have biases, congratulations!" I know, I know. But people seem to be so unaware of these biases and so confident in their unscientific assertions, myself included at times, I'm sure. We all exist in a bubble and are exposed to different media and different people. People disagreeing with you probably aren't always morons, maybe they've just been more exposed to things you haven't. Of course, people do make things up, but depending on how outlandish those things are, you might never really know. For example, I'm sure I could say things that would get me labeled as a "virgin who's never touched a woman," but that can be easily disproved by the fact that I fucked your mom last night.