detroit diver once bubbled...
NSS, and IANTD are advanced level courses. Other than the rare instructor that knows the difference (like MikeFerrara), and then teaches it, there is NO OW agency that teaches these fundamental skills in any depth to their students.
Your Advanced Nitorx Instructor MUST know these skills to do the cave diving that he does. He KNOWS why they are so important. You are lucky enough to have the benefit of his wisdom. You're right, you don't have to be GUE/DIR to push these skills. It's just that, with the few exceptions, no one does.
In fact, if you take a DIR Fundamentals class, the instructor will tell you that what they are teaching in terms of skills is in the first 4 pages of the PADI OW student manual! It's glossed over so badly that they have made an industry (albeit small) of correcting this oversight (I'm not sure "oversight" is the proper term, as I think it's deliberate).