Bullshit. Math requires a bit of wrestling with to master.
To be plain, I don't mean make it harder than necessary, be less than clear in explanations and demonstrations or whatever. However, math isn't just a collection of facts and formulas to be remembered and demonstrated examples to be regurgitated. The student must come to understand the principles involved and their application to problems which are not just like the ones shown in class. For many if not most students this understanding comes only after a good bit of work on their part.
I earned a PhD in mathematics and I can assure you as the level of study rises so does the outside of class effort expected of the student. Most people haven't encountered five problem homework sets that eat up the best part of two weeks to complete.
I think the issue here is you confuse teaching with lecturing. You expect to lay it out for them, then they make the effort to bridge the gap. That's not teaching. It's also nonsensical because the one holding the knowledge is the only one holding the materials with which the bridge can be made.
I always thought the problem with professors not teaching, especially in upper level courses, is they usually only understood the material well enough to use it. (Think of whatever is the math equivalent of physical chemistry.) To teach you have to understand it so well as to explain it to a six year old well enough they have at least a vague understanding. That holds with what you say. When you're at the cutting edge, you just got there yourself. And then there's the need to understand people well enough to guess where they are, too, in order to bring them to understanding. It's a special skill set few have.
