But there are people with great product taste who can know by trying a product whether it meets a real user need - some of these are early-adopter customers, sometimes they are great designers, sometimes PMs. And they really do need to try a product (or prototype) to really know whether it works. I was always frustrated as a junior engineer when the PM would design a feature in a written spec, we would implement it, and then when trying it out before launch, they would want to totally redesign it, often in ways which required either terrible hacks or significant technical design changes to meet the new requirements. But after 15 years of seeing some great ideas on paper fall flat with our users, and noticing that truly exceptional product people could tell exactly what was wrong after the feature was built but before it was released to users, I learned to be flexible about those sorts of rewrites. And it’s exactly that sort of thing that vibecoding can accelerate