In particular, since going to college is a normal bourgeois thing to do in America in 2013, doing it indicates that you are a normal American who subscribes to normal bourgeois values. A summer intern who's just finished up her third year at Yale doesn't have any kind of particular credentials, but we know that she probably has very good SAT scores and sounds like an exceedingly normal person. A young woman who got a 1600 on her SATs and has been spending the past three years working at 7-11 and watching Open Yale Courses videos sounds like a huge weirdo.
In lieu of actually applying, being accepted and paying tuition to Brown, after high school my friend Matt basically just moved into a house right off campus, lived with Brown students, sat in on lectures, etc. for a few years. Not surprisingly, this has not led him to a job at McKinsey, but he's certainly an interesting person, from whom I learned a lot when I moved here, e.g., the first time I heard the word "wiki," and he can say things like "Oh yeah, danah boyd, she's one of the first people I ever saw using the Unix shell."