Re: On who should teach beginners
Here's an idea.
A shihan might tell his seniormost students not to teach beginners directly because the student should be teaching someone how to be an instructor of beginners.
This would be a very bad system for a koryu or anything like it, where a certain form must be preserved and passed on for the purpose of effecting the changes in the student that the system is supposed to effect.
But I think I am qualified to say that Saotome Sensei has never been concerned with form, and he decided in the early 70s that the right thing to do to pass on what he got from O Sensei was to create his own organization, which is pyramidal in nature.
It is probably worth mentioning that the Yagyu Kai and most extant koryu organizations are not concerned with spreading their arts to the far corners of the world. If you want to teach beginners hands on it takes up a lot of your time and there are practical limits to the number of students you can have. Koryu don't care but Aikido needs to be more expansive if it wants to survive as an art.