I don't think this was supposed to be a feat of engineering. They're trying to create a site for a specific niche, seemingly targetting 25 to 45 year old design professionals. This is a bit like asking why are there so many vBulletin forums out there.
and I think either one is a valid question. what I meant was I wish there was at least some differentiation between stuff not just simple rehashing for different audiences, oh well.