In German university I did choose which lectures were worth attending in person (generally those where the professor was more insightful or entertaining than his slides or book alone), but generally attending the lectures wasn't the point. The lectures are the excuse to get people in the same building, get them to occasionally sit close to each other, give them topics to talk about and incentive to do so (when you've spent three hours on your weekly exercise that you have to turn in tomorrow and need help). It's also so much easier socializing if everyone has a valid excuse to drive there anyways; you might as well stay a bit longer avid talk