I think this ties into the importance of living knowledge. Even the most meticulous notes must be interpreted and executed by someone, and there is no substitute for an experienced person. This has already happened with technologies like vacuum tubes. It isnt a simple matter of economics to restart production because much of the know-how must be rediscovered. In the absence of the original volume of demand that led to the first generation of tube engineers, it may be lost forever. There are some niche high power RF devices still using tubes from decades ago.