Here's the thing: for the typical job listing, there are dozens, or hundreds, of applicants. Maybe more. You do not have the time to do a full-fledged investigation of every one of them, or bring them all in for a lengthy interview. You just don't. You need some filter to reduce the number to something more manageable, and degree/school is a straightforward way to do it. Also recognize that 99% of jobs, even technica…
Yes, it's impossible to interview every applicant, but a company focused on minimizing time spent and resources used instead of maximizing recruitment of employees who can create the most value is doing it wrong.