National graduates can't--and shouldn't--be fungible. Harvard, for example, selects and trains for team players. Its graduates can reliably be dropped into client-facing roles with minimal training. They're also extremely responsive to hierarchy. Their campus tradition champions the Socratic method [1] and deëmphasises individual performance. (The joke I've heard is an A is an A-, an A with a glare is a B and an A with a talk is a C. B means you effectively failed.)
Yale, on the other hand, is extremely competitive in terms of grading. Its graduates are ruthlessly ready to challenge hierarchy. This makes them great for internal situations where you need to inject disruption. They need polishing, however, before being placed in front of clients.
High achievers in a field should be diverse, in terms of how they work and approach problems. This is healthy. Degrees mean something. It's just that there's a lot else that's difficult to test for or assess in an interview that matters. What that "else" is varies.
[1] http://casestudies.law.harvard.edu/the-case-study-teaching-m...