I don't know why, but a lot of Redditors like to claim that only an incredibly low amount of women can cum from penetration.

It's usually like "penetrative sex isn't important to women, especially because only a very tiny amount of women can cum from penetration".

So, what does the science say? How many women do actually report that they can cum from penetration or are able to have vaginal orgasms?

Brody et al 2010: https://www.sciencedirect.com/science/article/abs/pii/S1743609515331520

In a representative sample of the Czech population, 1,000 women reported their vaginal orgasm consistency (from never to almost every time; only 21.9% never had a vaginal orgasm), estimates of their typical foreplay and PVI durations, what they were told in childhood and adolescence was the important zone for inducing female orgasm, their degree of focus on vaginal sensations during PVI, and whether they were more likely to orgasm with a longer than average penis.

Multivariate analysis indicated the most important predictors were being educated that the vagina is important for female orgasm, being mentally focused on vaginal sensations during PVI, and in some analyses duration of PVI (but not foreplay) and preferring a longer than average penis.

In this sample the vast majority reported that they are able to achieve vaginal orgasms, with only about 1 in 5 never having had one. 12% have one nearly every time they have sex, 15% more than half the time, 22% a quarter to a half the time and the rest less than a quarter of the time.

Costa et al 2012: https://www.sciencedirect.com/science/article/abs/pii/S1743609515338327

Three hundred twenty‐three women reported in an online survey their past month frequency of various sexual behaviors (including PVI, vaginal orgasm, and clitoral orgasm), the effects of a longer than average penis on likelihood of orgasm from PVI, and the importance they attributed to PVI and to noncoital sex.

Likelihood of orgasm with a longer penis was related to greater vaginal orgasm frequency but unrelated to frequencies of other sexual behaviors, including clitoral orgasm.

Women who prefer deeper penile–vaginal stimulation are more likely to have vaginal orgasm, consistent with vaginal orgasm evolving as part of a female mate choice system favoring somewhat larger than average penises.

Out of the 323 women 160 reported that they have had a vaginal orgasm, which is about half of them.

Brody et al 2011: https://www.jsm.jsexmed.org/article/S1743-6095(15)33296-3/fulltext

Women (N = 258, predominantly Scottish) completed an online survey reporting their frequencies of various sexual activities and corresponding orgasms, age, and the prominence of the tubercle of their upper lip.

An important caveat to this is that no matter how prominent a woman’s tubercle was, she was still more likely than not to have had a vaginal orgasm before. Specifically, at least 2/3 of women in each tubercle group reported having had vaginal orgasms. Thus, having a flat tubercle certainly does not mean a necessary lack of ability to orgasm—it just means a somewhat lower likelihood.

Here again the majority of women reported having vaginal orgasms. I couldn't find exact numbers, but in the group with the lowest rate of vaginal orgasms it was still about 2 out of 3 that have them.

Drasa Jr 2016: https://www.ijsr.net/get_abstract.php?paper_id=NOV162749

The present sample consist on 1275 coitally experienced women.

Women who reported that they were more likely to reach orgasm from PVI with a longer than average penis reported having more vaginal orgasms within a previous month compared with women for whom penis size is not importan

Women’s frequency of vaginal orgasm is associated with preference for deeper penile-vaginal stimulation, as indicated by greater importance given to longer than average penises

In this sample of non-virginal women only 5% stated that they never had a vaginal orgasm or that they have too little experience with PIV sex.

Herbenick et al 2017: https://www.tandfonline.com/doi/abs/10.1080/0092623X.2017.1346530?af=R&journalCode=usmt20

While 18.4% of women reported that intercourse alone was sufficient for orgasm, 36.6% reported clitoral stimulation was necessary for orgasm during intercourse, and an additional 36% indicated that, while clitoral stimulation was not needed, their orgasms feel better if their clitoris is stimulated during intercourse.

In this sample 18.4% reported that they can cum from penetration alone and another 36% that they can but that their orgasms feel better with additional clitoral stimulation. Which again is more than half.

Brody et al 2008: https://doi.org/10.1111/j.1743-6109.2008.00786.x

In a sample of 94 healthy Portuguese women, vaginal orgasm (triggered solely by penile–vaginal intercourse) was associated with less use of DSQ-40 immature defenses. Vaginal orgasm was associated with less somatization, dissociation, displacement, autistic fantasy, devaluation, and isolation of affect. Orgasm from clitoral stimulation or combined clitoral-intercourse stimulation was not associated with less use of immature defenses, and was associated with more use of some immature defenses.

A comparison of women (N = 69 who engaged during the past month in penile–vaginal intercourse) who had at least one vaginal orgasm during the past month and those who did not, revealed that women who reported at least one vaginal orgasm in the past month had less immature defenses (Cohen’s d = 0.81; large effect size), Isolation of affect (d = 0.91), and Autistic fantasy (d = 0.82) (all t(67) > 2.7, P < 0.01), less use of Devaluation (d = 0.78) (t(67) = 2.6, P < 0.05), and marginally less Displacement (d = 0.57; medium effect), Dissociation (d = 0.56), and Passive aggression (d = 0.58) (all t(67) > 1.89, P < 0.065) than women who did not have a vaginal orgasm.

69 out of 94 women in this study reported at least one vaginal orgasm during the past month.

Despite it being common knowledge on the internet research actually shows that the majority of women can have vaginal orgasms.

So why is it so common on Reddit that people deny this? Why do so many Redditors want to paint women as asexual beings that don't even enjoy sex?

And why is it mostly women themselves that do this? What do those women gain from claiming that most women do not like sex and can't cum from penetration?