I was predisposed to disagree with this essay, but it turns out I agree with some core observations, namely that most feminist movements have ignored the issue of race and class and have focused almost entirely on the concerns of affluent white women.
However, in the spirit of courting the ban-hammer, I am going to offer an alternative explanation. It's not "because Patriarchy", it's because women as a group have historically been complicit in the enforcement of social stratification. This is especially true of elite women, who are known to demand the most arcane and baroque observances of class consciousness. I'll add to this empirical evidence provided by the likes of OKCupid that women are, statistically, quite rigid enforcers of race and class boundaries, almost never willing to "date down". If women were the wonderful egalitarian creatures that feminism tells us they are, one would expect rather the opposite of what the facts show.
Ironically, I view women as simply people, radical as that notion might seem. That leads me to the conclusion that, with respect to ethics and morality, women and men are pretty much the same, i.e. they can be found in equal proportions on both sides of the moral spectrum.