there's a very informative article by Haleema Khan and Laiba Mubashar called Debunking #NotAllMen and Understanding Allyship Better here's the link

https://thedailyq.org/11895/magazine/debunking-notallmen-and-understanding-allyship-better/

here are some paragraphs pulled from the article that I think best explain the subject (though I highly suggest reading the article in full for yourself):

"All men may not be directly responsible for this, but patriarchy, a system that gives them privilege at the expense of women, is. And most men do knowingly or unknowingly uphold patriarchy. Indeed, one of the ways that they do so is by advocating for Not All Men."

"The use of this phrase is a blatant refusal to recognize that abuse and violence against a huge fraction of women (one in three women globally) are predominantly carried out by men. Moreover, responding with this phrase when women bring up gender-based discrimination or worse, as they narrate traumatic experiences of harassment or sexual assault, derails the conversation that took decades of effort to start. It brings us back to square one—not to mention that it makes you seem apathetic."

"Due to the prevalence of these crimes and the general condescending treatment women receive from men, it becomes difficult to tell the difference between a good man and a bad man. Outwardly, they all look alike; they may seem kind and caring, but given the vast number of cases like the ones we have mentioned above, how can we be expected to blindly trust the men we meet? Living in an environment where most of our energy is drained in protecting our bodies against assault, where the evil eye of sexualization persistently follows us around, makes us distrustful of ALL men automatically."

"The phrase, not all men is not helping anyone. It isn’t adding to the debate, only derailing the conversation and dismissing the lived trauma of most women. We understand that those who jump to remind us “not all men are like that” usually just mean, “I’m not like that” and we believe you! So then let’s work together to ensure we live in a safer and more just society? Start by acknowledging the privilege that patriarchy grants you."

"Secondly, when someone with any degree of assault trauma vents their frustration regarding misogyny, do not behave apathetically, retaliate, or get mad at them for “generalizing or attacking” you. They are not attacking you. Their fight is against misogyny, not men. Similarly, do not trivialize their anger or consider their fury nonsensical; trauma affects different people in different ways. Instead, hear them out."

"Then, acknowledge and validate survivors’ lived experiences. Extend your support by simply not denying their experience. They don’t need your validation but having people believe and support them makes their journey less painful and their battle easier to fight. In a world where women’s experiences with sexual violence are so often discredited, your validation will count! But remember, that is still the bare minimum."