Even the loss of institutional knowledge can degrade the safety of a system over time.
Ever had to start maintaining a codebase after the greybeard who made it retired? Did you have any documentation to go off of? Anyone remaining in the company regard it as anything other than a production critical black box?
Now imagine that codebase is an industrial process, with 20 years of growth, add-ons, changes. Probably some mismatching control systems, and god only knows if the as-builts or red line plans for the additions are all correct or rectified with each other..
Ever had to start maintaining a codebase after the greybeard who made it retired? Did you have any documentation to go off of? Anyone remaining in the company regard it as anything other than a production critical black box?
Now imagine that codebase is an industrial process, with 20 years of growth, add-ons, changes. Probably some mismatching control systems, and god only knows if the as-builts or red line plans for the additions are all correct or rectified with each other..