Over and over, it happens that when essential people are lost, their essential knowledge is lost. Nikon had a hard time replicating their 50's rangefinder cameras 40-something years later because the people who had made the originals were gone. They never did figure out for sure how some things were done originally. This despite having more modern materials and techniques at hand, and the latest knowledge. In a time of sophisticated design and manufacturing techniques, the regard for pure cleverness and a sophisticated soft knowledge has been reduced. Schools could never really teach the ways of thinking that people needed in the past to solve problems. Only long apprenticeship could accomplish that.
From reading the posts of PE and others from the business, it's clear to me that film production is, as the saying goes. "as much art as science". For all the modern scientific understanding of materials and processes, and advanced tools, it still takes people with insight and judgment to successfully create the product. Lose them and you're screwed.