You end up with a far less merit based hiring pipeline. I work at a top tech company and don't have any degree at all. The current process gives people like me a chance, yours wouldn't.
i interviewed a while ago at a FAANG where they had a long standing problem related to their OS. i knew the solution because i recently brought a product to market built on top of a similar OS and had to address the same problem.
but it was more important to them i passed their coding test within a few minutes, and that i choose the optimum solution, which can only be found if you can spend an hour thinking about it. i bombed the interview due to not being used to coding interviews and having to talk while i think, and having to do all this in a few minutes.
they are probably still wondering how to fix their problem.