There have been studies on chimpanzees showing that female chimps choose girly toys (dolls etc), and male chimps choose male toys (weapons, trucks etc) without any outside influence. Yet people act like the human species is different. They believe people only become who they are because of indoctrination into their respective gender roles.
Then when you call BS on that... you're called a sexist. Then when you say "YES I AM A SEXIST" you're called a misogynist. I don't see how treating women differently (better in many cases) leads to "hating women."
As for marketing - I think women do choose products differently than men. It's because they're wired differently. They are more likely to choose products based on sentimental or perceived social value. If you look at the majority of Meyers-Briggs personality types among women, there aren't as many INTP,INTJ or other engineering types. Even if you don't agree with Meyers-Briggs... that there exists such a strong difference between the male and female population that an INTP (my type) is 4 times as likely to be a male, it should prove there are major differences.
The end result of these differences is that you should buy the woman you want to marry a diamond. As an INTP I know it's illogical - but I can accept it since I believe women and men are wired differently. I feel sorry for the men on HN who believe otherwise and are going to argue against diamonds with their future wife. (good luck with that - unless she's an INTP)