Status: work in progress/noodle. Not fully fleshed out.
Systems of dominance and oppression often have end games. Highly xenophobic people often fantasize about deportation and genocide of the opposing group. In the United States, white people who love dominance over black people don't want to genocide them, but to turn them into perpetual servants. Anti-gay people know they can't get rid of gays as homosexual desire seems to be innate, but they do want to make homosexuality unmentionable. The point is to drive the hated group into such a weak position that it will take them centuries to get out of their oppression, if they ever can.
Because women are necessary for reproduction, men cannot get rid of them. What is the goal, then? What is the point where women are so weak that they cannot fight back? I've been reading the works of Alice Evans, who writes about patriarchy and women in labor around the world, and I believe the end game of patriarchy is female seclusion. When women are unable to appear in public without becoming victims of violence, they effectively cannot advocate for their rights, make their own money, meet other women, or escape the men in their lives. These women are extremely vulnerable and men can do what they want so long as it does not infringe on what other men want - women are turned into broodmares, unpaid maids, psychologically molded to be nothing but assistants to men. Their desires are stamped out, and if they still have a hint of self to them, the material reality that they cannot appear without male family in public makes them unable to escape.
Culture has been the most powerful way to enforce this, entwined with religion. Cultures where women as a group are the least powerful are ones where women are unable to appear in public without being branded as whores, and therefore considered acceptable prey. Ancient Greece, ancient China, the middle East, parts of India, the list goes on. Meanwhile compare societies where women are allowed to appear in public - they are far from utopia, but women have the capacity to accumulate power. The Iroquois, and Benin society immediately come to mind.
A society can be patriarchal and woman hating while allowing women to appear in public, of course, or may have different levels of allowing women to appear in public. But once women are not allowed to appear in public, it becomes extremely difficult for women to get together, to appeal to other women.
Note there is a difference between separatism and seclusion. Women wanting to get together with other women and excluding men is not 'seclusion' - these women are choosing to focus on women, not thinking about men, and are able to re-enter public life as needed. They may even be publically separatist and choose to only pay attention to other women. Secluded women don't have a choice. They are under the aegis of men, and the women who enforce those men's wills.
Seclusion operates on a public-private distinction. Private women are a form of private property, and are to be protected (and abused) in the same way a man may protect or abuse any piece of property he owns. Public women suffer the tragedy of the commons, since they have no protector and therefore may be attacked by anyone. Public women are held up as examples to private women - if you do not behave, we shall cast you out onto the street, and you shall be forced to be a public woman.
(Ironically, prostitutes and other sex workers have found ways to establish independence this way, see the 'hetaira' of Ancient Greece society. In the end, though, courtesans and prostitutes, even successful ones, have to rely on men's money and goodwill just as secluded daughters and wives do. Courtesans may just have a little more room to move, because being in the public sphere they have larger networks. It's a topic for another article.)
This is why feminists must never defend systems of female seclusion, and must make the distinction between seclusion and separatism. Seclusion puts women at the mercy of men (and higher ranking women who have survived the gauntlet and now want to take it out on younger women - mother-in-law versus daughter conflicts). Conservative forms of religion and culture therefore must be criticized on these grounds. It does not matter if the women in ultra-conservative religions claim to enjoy or prefer it. Once again, the mother-in-law may feel accomplished that she survived the gauntlet, but will her daughter-in-law feel so lucky being lorded over by husband and MIL? The fact is this system allows for no choice but seclusion. The happiness of the women who managed to find a position for themselves can never outweigh the very harm this system creates for girls and women materially and psychologically. Conservative patriarchal religions must be given no quarter - they will give women no quarter, either.