It seems to me (at the moment) that the 'engineering' of "prompt engineering" happens at the level of taking a word prediction model AI and turning it into a Q&A AI, and the art of decomposing requests into state and behavior that can produce an A from a Q. Also the chaining of prompts, self prompting, etc.
It's functional composition that's interesting. A system of prompts. Not the phrasing of a single question, no matter how clever.