Why does removing all segregation help stop women being unfairly limited, etc. Surely what would help with that is the destruction of gender. The actual un-artificial issues women have to do with their sex, their vulnerability to males, is not going to change.
You've got it backwards.
Firstly, I didn't say all. I explicitly said we don't need to set a specific target.
I'm saying assume we don't innately need sex segregation, work towards that, then where/if we find we do need it, keep it.
That's not the same as saying it's always bad.
I'm saying question it. I'm not saying remove it arbitrariily.
Secondly, on "Surely what would help with that is the destruction of gender."
Sex segregation create issues as well as solve them.
Women's private spaces, for example, exist to remove both the physical/sexual risk of assault and the emotional strain of being alert to that risk all the time, of feeling unsafe or encrouched on by men.
However, the reason some men have a "womens toilet" fetish is exactly because it's a place they can't go, associated with a part of the body they don't have and is considered transgressive to see.
Right now, those men exist (oh how they exist) so we have to keep them out. That's non-negotiable. But the very act of keeping them out also perpetuates the dehumanising of women as "other" or "mystery".
Obviously we can't solve that by getting rid of single sex spaces while we still need them. But you can recognise that enforced (as opposed to voluntary, like your example of the women who spent a lot of time apart from their men but sometimes come together) sex segregation has repercussions in artificially over-emphasising the importance of differences between men and women - in other words, allowing gender to creep back in.
But your utopia of no sex segregation relies on not one single man being dangerous to women and using his superior size and strength. That will never happen. Otherwise you're saying it's fine to sacrifice a few women to the greater good of no segregation and the (IMO) myth of the sexes being identical.
As you say, it's a Utopia. It's not supposed to be a blueprint for feminism in the real world - not a target, remember - it's supposed to be an ideal to measure against to stop us falling into gendered traps. We should always ask why we need a specific supprt or segregation. Does that reason still hold? Are we allowing the existence of the support to let society off the hard work of actually dealing with the underlying problem, or is this a fact of life that will always be with us? Because Gender, Sexism, Unconscious Bias, whatever you want to call it - this thing doesn't come with a label saying "fake" so we can all see it for what it is. It pretends to be "natural", "the way things are", "innate differences".
It's also not "not one single man". It's "men are no more a risk to women than other women".
But the idea of "sacrifice a few women to the greater good of no segregation and the (IMO) myth of the sexes being identical" is also a misrepresentation. It's not about some theoretical idea of equality - remember, it's not a target - it's about a balance between the risk to individual women from men and whether we can reduce that at source rather than just remove the women, versus the harm done to women as a whole by perpetuating the segregation that emphasis our differences and causes men to other and fetishise us.