I believe this because every time I use AI for domains that I consider myself above competent, if it is anything beyond UI components or a simple CRUD endpoints, I cringe at the quality of what it generates.

In a long run session Fable 5 generated a Disney principled (physically based) shading/lighting engine from scratch, both with a CPU (SIMD accelerated) backend _and_ a full GPU Vulkan backend. Exceptional performance too; the CPU backend runs almost realtime and literally looks better than some AAA games outright. Took it about ~8 hours wall time total time to achieve this.