Re: The "real" techniques not taught to everyone?
There are a lot of perspectives regarding the topic of this thread which haven't been discussed: The cultural perspectives of the west vs. east, the responsibilities of a Soke vs. the responsibilities of a student, and finally, imposing a dichotomy on an issue and rationalizing it without exploring other perspectives.
The so-called 'western' mindset views teaching much differently than the so-called 'eastern' mindset. In the west we expect to have everything given to us by the teacher -- we unconsciously believe that this is the teachers responsibility to fulfill. However, the student has the responsibility to learn, and no amount of teaching will change this varying ability of a masters students to respond to the teachings of a ryu.
A master looks for one student who is capable of living up to the responsibility of Soke, and passes on the knowledge of the ryu to ensure its survival. This may be done in secret to protect the traditions of the ryu, hence explaining why some have been admonished to hide their knowledge until they have passed it on.
As a side note, there are things which we learn as martial artists that can't be written about; they are beyond technique. There are also things which can't be taught. This is the responsibility of the student.
Many are shown the same technique, and many do not understand it, but a fraction do. It isn't that different from the statistics regarding what percentage of students achieve a dan rank, where applicable, and those that continue to deeper levels of training. This is the responsibility of the student.