Because a forum that segregates answers by sex lends itself to attention by both sexes to questions which favor this arrangement. Naturally, sex, relationships, and flirting are the topics which gain the most from having sex segregated opinions. Sex is, among this short list, is the most taboo to openly discuss in person. Ergo, sex related questions are the ideal question for this forum and consequently, they get the most attention because the related questions prompt redirects people who gave opinions to questions related to sex.
LOL. I don't pick particularly. I just try to answer all the questions. Sometimes i just stare at them for 5 minutes and just close the tab. Maybe i didn't know a valid answer or I couldn't put it in a understandable way for the asker. I don't have much experience in relationships, break ups and stuff like that. I don't want to mislead people with my answers. So, I don't post my opinions, unless I'm sure of it. Most of the sexual questions are easy to answer. Because even some rude answers are taken lightly. But in other questions people get pissed easily.