The spec, or prompts system, whatever you call it, is more like a recipe than code.
It doesn't automatically generate the dishes; a good cook is still needed.
I disagree with the OP that AI coding can't be taught. My answer to why so many people have trouble would be that they refuse to learn. I see tons of people who are insanely biased against AI and then when they try and use it they give up after the first go (having tried a horrible application of AI like making a functioning production app with 1 single prompt, no one using AI for work is using it like that). They also don't take any suggestions on using it better because "I've tried it before and it sucked."
If you asked me months ago whether "prompt engineering" was a skill I'd have said absolutely not, it's no different than using stack overflow and writing tickets, but having watched otherwise skilled devs flounder I might have to admit there is some sort of skill needed.
I fully expect that in 1-2 years that SWE curriculum will have AI coding as a major feature. The question I have is will students be required to do their first year or first assignments in a given course without AI.
My ex teaches UX. We were talking about AI in academia last week. She said that she requires students to not use AI on their first assignment but on subsequent ones they are permitted to.