More personally knowing the person. You develop a friends network of people, and everyone in that network is credentialed enough to get into a college and do reasonably well. So they'll get opportunities, and help you get opportunities.

Speaking primarily from my experience as a Comp Sci undergrad at Virginia Tech... I had good opportunities from my network on graduation. Which helped me grow my network even further when I got a job. I suspect if I went to MIT or something, that network would be even more substantive.