think about a cocktail party. the host comes in, introduces everybody around. you meet new people, talk about stuff. generally a good host will tell you a little about the other people you haven't met, and say something like 'they'd be a good person to talk to about X', where x is some topic you know you have in common. most dating sites don't do this -- there are no introductions, no incentive to converse. you get to know/be comfortable/uncomfortable with people through interaction. a guided interaction is exactly what most online dating applications are missing.