Perhaps I live in an area with more segregation of the sexes, but there is absolutely a divide between men and women here. Stepping out on a limb here, but I would say there's also a divide online given the fact that we need our own community where no men are allowed to post or reply. This post itself is an observation on the differences in view of masculinity and femininity between men and women. Quite frankly, compared to calling masculinity arbitrary, I think my point was quite tame.
My original statement is based upon my lived experience. I appreciate your explanation as to why I'm wrong, but as I asked before: what would be a good way to degeneralize?