IMHO, it's a people Thing. People developed better practices, talked about IT in conferences, maybe left the company. AS a result the knowlegde spread. On the other Hand, If the places where a skilled individual can work and honey their skills, the knowlegde become scarce, the knowlegde cannot spread anymore and it will vanish. If you only program with AI and 5 people do the Work of 100, then you end Up in such a scenario.