Which, even more than not wanting the information to get into "the wrong hands," could be why the subject is not more openly explained in all the books that deal with it.
This stuff gives an unmistakeable edge, no question. So in ancient times, you didn't show everyone those things which gave you a survival edge. That was "the wrong hands" in those days, but "the wrong hands" idea is morphing somewhat in these days of guns, etc. My idea of the "wrong hands" has to do with the emphasis that there is always more information about these skills that you didn't know... so the guy who stops at any stage (often as soon as he declares he's teaching the subject in some way) and declares that he has arrived and is a "teacher" is often the guy I have in mind as "the wrong hands". But only for the reason that he's doing a disservice to his students, etc. I actually have some pretty good information-exchange conversations on other forums with guys who I don't personally care for, but they have knowledge and they're not into playing a role as a teacher. So they're not what I would call "in the wrong hands", if you see what I mean.
Each level of knowledge is only the entryway to the next level of knowledge. Anyone who is arrogant enough to point out the lowly level of people below him is the sort of person I don't want to tell anything, frankly. He appears too much to be into these things for self-aggrandizement and not enough for the pure chase of the knowledge. Role players need not apply.