This is not true in my experience at all. I never write such detailed spec for AI - and that is my value as the human in the loop - to be iterative, to steer and make decisions. The AI in fact catches more edge cases than I do, and can point me to things that I never considered myself. Our productivity has increased manyfold, and code quality has increased significantly because writing tests is no longer a chore or an afterthought, or the biggest one for us - "test setup is too complicated". All of that is gone. And it is showing in a decrease in customer reported issues