“ The person proposing has been thinking about this for weeks or months. They've tested pieces of it in their head or even built proofs of concept. They understand things about the idea that aren't obvious yet. And they're trying to explain all of this to a room full of people encountering it for the first time.”

This is just not true in my experience, and doubly so after the advent of LLMs. I've seen more half-baked ideas presented than thorough plans.