I was totally with you up until the "discussion section" part. Isn't that the sort of thing that makes great colleges really great? The professor is not supposed to just give you the answer to Plato's Allegory of the Cave. He is supposed to give you the opportunity to consider the "answer(s)" for yourself. The professor's job is to ask questions that never even crossed your mind, thereby expanding your intellectual horizons when you go looking for the answer. And yes, partly, I'm sure it is about getting students comfortable with the idea of expressing and defending their opinions in front of their peers.
But yes, it is super annoying when the same people keep going on and on. Professors should definitely step in once they start getting redundant and allow others the opportunity to speak.