[drobert]

Practically companies outsource the recruitment process to schools. To get in a top school you need to have passed certain filters so it is more likely that talent can be found there. It's applicable is any country not just USA and in sports as well.

It's a hierarchy building system that works but of course it's not perfect.

If you are presuming that untapped talent exists in lower ranking schools on a large scale, companies would shift their recruiting strategies because people from top schools require much higher starting salaries. Leading companies recruit from top schools to remain in the front.

The hypothesis that some groups (black, women, lgbt, etc) are systematically marginalised is not compatible with capitalism. While it has an element of truth due to the in-group preference (which a very natural phenomenon - even trees do it) in a ruthless market companies which discriminate are at a loss - they loose star employees and eventually their leading position. If huge untapped potential exists in the marginalised groups this would create a market opportunity: companies could only hire from these groups and outperform the others. I don't see this happening.