90% of "history" in martial arts, IMHO, should be considered historical fiction; books like, "A Killing Art", are propaganda and myth.
I'll let other people deal with this statement. It seems like a gross generalization and white wash of plenty of good scholarship.
Hidden techniques are the same; those of us who trained in the late 70’s and 80’s learned very “simple” explanations to our forms but now the cult of “boonhae/bunkai” is in vogue. Don’t spend too much time looking for “secrets”, train hard and never quit and you will learn the real secrets.
Based on my research, it's a good chance you did NOT learn any real applications of the forms in the 70s or 80s. I don't know who your teachers were, but if they were connected to any of the kwan heads and you did not have access to Okinawan Karate training, then I would say that my comments are probably on the mark.
The bottom line is that Koreans did not learn the applications of the forms from the Japanese or the Okinawans. They did not understand the applications for the classical karate kata and when they remixed them to form the "Korean" kata they still did not understand what they were doing.
When I say "do not understand" I am very explicitly meaning that they were not taught what these moves really were for. The Korean Masters certainly invented a system of understanding the moves that was very complicated, but that system is demonstrably less effective then the system that was originally extant.
The group of people involved in researching and changing the curriculum of the KMAs back to close quarter self defense based art is doing nothing cultish. To label it that, IMO, really just labels you as a reactionary who is very resistant to change. You may have learned your art one way and if you want to practice it that way, I have nothing against you at all. There is no need to disrespect people who may have discovered what they see as gaping holes in the credibility of the kwans and want to correct that.
I truly understand how some people can feel resistant to these changes. I put a lot of time into learning my art and one wants to feel like that time was worthwhile and spent training in the best way possible. In a way it was, because you train the best you can with what you have. This information gives us more and the delusion that the art we practice is perfect is the only thing that prevents many of us from seeing how we can have more.