Which is a result of our nature. Men were meant to provide protection, shelter, etc. Women are to provide heirs and sex. So our nature compels us to be protective of women. Furthermore, most (unfortunately not all) people grow up being taught to respect women and be courteous. This is a result of the 'chivalric' era. This is why men are supposed to hold doors open for women, seat them, etc.
But of course, the biggest factor is that this is a community of nerds..