taking an oral exam is different from being able to discuss something. you know as well as i do there's a difference between a regurgitation paper and one that requires you apply knowledge to analyze something else.

the kind of questions i'm talking about are application. like for a programming course you might ask what features of a particular language one might explore for solving some vague problem and why. for history pick some current event and ask about its parallels to and lessons for something happening today.

harmonic analysis is probably one of the worse use cases for this. and yeah i agree with open notes exams.