Do students want to be told what the right answer and explanation is without all this self discovery, group learning, etc?
And the book: the details are left for the student to work out.
Above thread has students who want to be told something or other by math teacher/prof. They don’t seem to be asking for self-discovery in the library.
Do students just want it explained? The explanations of other students are not as complete? Have gaps? Jump around?
Some search results that argue in favor of not just lectures.