Personally I find that HN is a nice place to get away from the non-technical side discussions that take up so much space on Reddit, Google Plus, etc. Discussions about sexism fall into that category for a technical site (elsewhere they would certainly not be side discussions).

While they're important, I have other places where I know that non-technical discussions will include those topics (and they often do on a daily or weekly basis). In the end, a site about technical and technology news should avoid controversial topics, much like a political site should avoid technical topics.

Just my $0.02.