When companies like Meta or Microsoft lay of experienced people or make their lives so miserable that they voluntarily leave, they are unknowingly erasing institutional memory.
Every company's infrastructure is chock full of Chesterton's fences and stays up because of unwritten processes.
The code bases are typically huge, so nobody can understand them end-to-end. When the people that know the history are gone, the only thing the remaining crew can do is fight fires and make cosmetic changes at the edges. Rewriting from scratch is not an option since, as your favorite AI will say, the software has become load bearing for the company's success.
The good news is that I think for green-field code, vibe coding offers a way to avoid this trap by embracing the invariant that all software should be evolvable without any human needing, or even be allowed, to understand the inner workings of it.
Only if you take the human developer completely out of the loop like this, you can ensure that software never atrophies into legacy software.
This may sound radical to AI coding deniers, but the reality is that code inevitably becomes incomprehensible for humans, so the rational solution is to just assume it is like so from the start.