It also keeps the base those that have the privilege to turn down other jobs and focus solely on getting hired at Amazon (or other FAANG) right out of college.

It also keeps the base those that have the privilege to turn down other jobs and focus solely on getting hired at Amazon (or other FAANG) right out of college. A good chunk of folks (among whom exist great developers) are those that are focused on working a job while graduating, and getting to a point where they have stable finances. Then they focus on things like "what kind of job" do I want, and "where do I want to work". That could be years and years down the line though. So it enforces an aristocracy / pedigree of sorts, but folks are hesitant to admit as such.