The situation gives men an enormous advantage. And the vast majority of the 90%+ of Fortune 500 CEOs and tech startups and VCs who are guys don't seem to have any interest in changing it. Why do you think that's the case?
My hypothesis is that the society unconsciously believes that aggressive "pushy" women would make bad mothers or would be otherwise somehow bad at raising children. But would they really? What if strong women give birth to natural leaders, to put it figuratively? Human societies have a tendency to place higher value on things like complacency and moral propriety, even if those things could be detrimental at the individual level, and a related tendency to ostracize those with high social intelligence or manipulative traits even though those traits could be beneficial at the individual level. What if the "bitch" stereotype is due to a similar effect?
EDIT: if you disagree with me enough to downvote this, I would love to hear your opinion on why precisely you disagree, so please comment.
It's more that the people at the top have gotten there in the current situation. So emotionally they tend not to want to acknowledge what a huge advantage they and their peers have had getting there ... and they don't have any incentive to change things in a way that reduces that advantage.