The modern software development ethos is based around the idea that you don't know to what destination you're ultimately going.

If you missed your destination, the solution isn't to think deeply about where you're supposed to go, it's to drive faster towards the next goal, so that if you make a mistake, it's not that big of a deal.

The slow moving projects didn't have some magic knowledge about where to go, they made the same mistakes but at a slower pace.

But all of this relied on the fact that code went through the brains of a human and said humans intelligence gets updated from the feedback, so that the developer builds a theory/model of what the software is really meant to look like in the end.

With AI, there is no such model. A context window is more like a tape or a film. The human is still responsible for building that mental model.