No, it's not a joke. I'm not talking what men should do, I'm talking how evolution has designed both men and women's bodies. By the nature of how we're built, it's going to be harder for women than men. Evolution doesn't care about how we feel, it cares about women 'leading' the men to the end, so to speak. If it were the reverse babies wouldn't get made.
I agree with your analysis, though.
There's a problem with your theory. It assumes that both men and women have sex until they cum, and then stop. Well... women rarely need to stop after cuming. All an orgasm does for a woman is make her like you more. There's an evolutionary advantage to be liked by the woman you're fucking. Especially since women are sneaky, and don't advertise their fertile periods.
If we're talking basic design. The human penis is shaped to create a vacuum and suck out cum from the guy who was there before. Also, only about a third of our cum can fertilise the embryo. The other 2/3's is designed to hunt down and kill other men's sperm in different ways. We're designed to cum after we've pumped enough to allow any prior cum to get sucked out. That's why we don't cum immediately upon entry. We're designed for gang-bangs. But does that mean that any sex with a woman that isn't a gang bang is doing it wrong?
Of course it doesn't. It's great to have optimal equipment for gang bangs, if that's the kind of sex we're having. If we're not having that kind of sex, having the gang-bang equipment doesn't hurt.
And since no animal is capable of having sex that isn't natural to it's species, it means that it's natural for humans to not only have gang-bangs. Since most people clearly aren't.
Gang bang equipment on a man who never has gang-bangs is just genetic drift. Useless evolutionary designs are only dropped if keeping them around has a cost.