Earlier quoted context omitted.
There is something different that happens in a vertically integrated engineering firms. In the event of a critical defect - very senior engineers will find out the specific people who caused the defect, and vet that the appropriate corrective actions have taken place. Likewise, if you do your job well on sub-assembly 529ca - you have the opportunity to be noticed and move up to bigger projects without changing firms…
You raise a very good point. If you join a company with the goal of retiring in the same company after a a 40-year career, the incentives are much better aligned than with contractors. Maybe the demise of the 40-year career in modern companies is one of the bigger elephants in the room
In theory, you can pivot the entire knowledge "supply chain" to a different problem in 1-2 years in this manner. Shifting a contracted supply chain could take decades if it was even possible.