also some 3rd party libraries are overdesigned/overcomplicated because everybody wants the library to do everything for everybody.
This overcomplication can easily introduce security problems that is not present in the 1K solution.
Also a source of significant dependency churn even excluding security bugs.
Whereas with my own code I don't have to worry about scheduling work that's only arisen because somebody outside my organisation has decided to make a breaking change in a dependency. Paying that tax got old over a decade ago, and my patience with it now is close to zero.
Of course, sometimes simpler is “I stored the passwords unhashed”, so you have to find the middle ground.
The point being, if you weren't committed to maintaining your own implementation of a library before the advent of LLMs, having access to LLMs does not fundamentally change the calculus. The ability to generate code more quickly does not automatically grant an organization the capacity to maintain more code.