I think the real reason people dislike sexism discussions is because there's not a whole lot rational discussion to be had about it. If you try to make a point about a single aspect you might disagree with, you get shouted down as sympathizing with sexists. There's no winning and there's no minds to be changed.
I reject this assertion. I am certainly not sexist, but I flag stories like these because they belong on Reddit discussion forums. Hacker News should be for tech-related discussion, in my opinion.