I retired three years ago but have many times reflected on this issue of lost corporate knowledge and it even came up again this week while talking with a friend.
I was in PR/advertising The relationships I built with editors were invaluable to my success, but not even considered important to the company when I was leaving.
25 years ago when I was with another company, a man on the board of directors was very much concerned about this issue. He said that companies need to build "a corporate brain" so that the intelligence learned was still available after employees left.
I myself published an article last month about the importance of a company's database for marketing. This, too, is part of that corporate brain. I cited a company that hired a regional sales manager but because wheir own database had been mismanaged and software nt kept current, the sales manager did not even know the names of the contacts he was to manage, or the products they had bought or anything else about these customers (or whether they were even customers still.)
That is BASIC knowledge, and woefully illustrates what gets lost when you fail to value it. (I'd be curious to know if the company is even still around.)
Anyways, good article. Stimulated my little grey cells.