See, I agree with you, but look at it from the average person - they now have to stand up in front of a crowd which will probably freak them out due to public s

See, I agree with you, but look at it from the average person - they now have to stand up in front of a crowd which will probably freak them out due to public speaking, plus the self-consciousness of being the odd-one out in a room full of your peers plus the embarrassment of interrupting the lecturer can compound into a situation that most people would rather avoid. And yes, there are lecturers who don't mind answering questions, but there are very few students who have never met the grumpy, tenured "I don't give a fuck, I lost faith/hope a long time ago" professor who will go out of their way to make sure they aren't bothered with questions while they talk.