I don’t know much about medieval universities, but maybe this thing was popular because the subjects are sort of vague and subjective? Like maybe a powerful placebo could make you feel you’ve improved at “eloquence” or “dialect”, but it certainly wouldn’t make you able to compute wavefunctions for quantum mechanics. It’s pretty hard to imagine people trying something like this to learn the material for a present-day physics or CS degree, for example. You’d pretty much immediately realize it’s not working.