I would say it is just a different way of teaching and probably also a way of creating an opportune niche, at least for some time. Every student would eventually figure it out and be able to differentiate between the two and I am sure they would have been able to describe the difference if they actually tried, just were not willing to and the more polite and unproblematic way of saying "no" would be to say "you cannot describe it, you can only learn it at that one place in Japan".