Popularity, I guess. It became a very general interest site that covers a wide range of interests, and therefore appeals to an equally wide range of visitors -- including those with, shall we say, poor taste and etiquette. HN, on the other hand, is largely centered around the working programmer, a group of people who, for the most part, are looking for something interesting rather than memetic jibber jabber.
Popularity, I guess. It became a very general interest site that covers a wide range of interests, and therefore appeals to an equally wide range of visitors -- including those with, shall we say, poor taste and etiquette. HN, on the other hand, is largely centered around the working programmer, a group of people who, for the most part, are looking for something interesting rather than memetic jibber jabber.