IMO, fundamental education, and the teacher make an art complex.
Fundamental education, in that a person has learned enough, not necessarily and not even primarily in martial arts, but in life experience, that they can make intelligent logical correlations of what is grounded in worldly reality and what is fluff, or at least more so than not. It can become more apparent after being in the TMA community for a while, meaning being aware of other schools/styles/training out there, and observing.

The teacher, if they make it complex, it will be complex, especially if the student lacks fundamental education, or is gullible enough to become entrapped in the hocus pocus and all the Carradine-esque confucian like statements.

When I first started training, I came upon VHS videos of Hai Deng doing a one finger handstand against a wall, and poking holes in sand bags. I saw "monks" licking glowing red hot iron shovels and showing visibly impressive feats of flexiblity, and what looked like the ability to resist damage from wooden and metal attacks. I read stories of Wang Ziping growing a tree, and as it grew, jumping over it daily until he could jump over a seven foot tall tree, and defeating russian a Russian strong man with his kung fu. I thought if I could learn the "secret" , I would be "the deadly".
After a few months when I got into sparring at the school, both my Sifu and the chief sparring instructor let me know that there was no "d3adly". Just to keep training and improving.
Down the line, I discovered there was plenty of fluff in what I was learning, probably even more so now than then. But there was also some really good solid "simple" things that were and are taught, and although fighting can be attributed a lot to the individual, it still says something about the system if a bunch of individuals succeed well under the same training. So either, the place just attracted already decent fighters, or the training/teaching/learning had something to do with it as well. I believe it was the latter.

Although an already long post here, I'll continue to the next point.
I still think it is plausible for there to be a great training method, but very few with the ability to teach it properly. For something to be considered great is really subjective, and can be independent of how well one or some can teach it. There is also the possibilty that something is at or not far from it's inception, so it could be logical that there wouldn't be many to teach it, and of those few, it is certainly reasonable that a minority may actually be able to teach it (communicate it) well.