I would say some of the students in the article probably aren't SV material - "They’d begun studying computer science in college"? So you've been involved with computers for 4 whole years and you think you're qualified for a top tier job? I'm sure not all of the students only started in college - I'm also not naive enough to think there isn't prejudice in SV, but didn't start until college...
I think its kinda ridiculous to say that to be 'SV material' you need to have started studying CS before college
By the way, this has been brought up as the reason for the dropoff in the women who enter CS curricula in college. Ever since home PC's became affordable, freshman CS classes have basically assumed prior (and thorough) computer experience, and many women who might otherwise become good programmers, for whatever reason (society influence, etc.) have had waaaay less hands-on time with computers than boys, when they become freshmen.
That said, I have met some excellent programmers who started out doing something that is superficially completely different (musicians, for example).