A degree is like a past proof of minimal performance - ie that you did barely enough to satisfy the requirements at one point in the past. The requirements may or may not be relevant for the job at hand.
A degree doesn't says how good you are either.
Yet many people use that as a proxy, maybe to save themselves the trouble of properly evaluating candidates.
Why not - but they shouldn't complain about mediocrity then. They fuel it (along with the education bubble)