It's like saying "I want a bridge" and then expect steel beams and cables to appear (or planks and ropes) and that's all you need. The user needs are usually clear enough (they need a way to cross that body of water or that chasm), but the how is the real catch.

In the real world, the materials are visible so people have a partial understanding on how it gets done. But most of the software world is invisible and has no material constraints other than the hardware (you can't use RAM that is not there). If the hardware is like a blank canvas, a standard web framework is like a draw by the numbers book (but one with lines drawn by a pencil so you can erase it easily). Asking the user to code with LLM is like asking a blind to draw the Mona Lisa with a brick.