Often it is not possible to separate the technique from the man. Things like riding a bike or flying a helicopter come to mind. A lot of what makes a master good cannot be written down anywhere. There isn't anything tangible to actually lose.

How would you write a document that describes to someone how to ride a bike or dig holes efficiently? You could explain the principles and general ideas, but the apprentice is going to need to get scraped up a bit before they actually learn anything that matters. The apprentice willing to suffer repeated failure is where most of the heavy lifting occurs. The master is mostly a backstop to keep the apprentice alive.