[eberyvody]

never have i ever been involved with a _successful_ software project where product decisions were made entirely by product people and handed off to design/eng.

in my limited experience, good product builders exploit leverage points that in order to solve customer problems / test assumptions quickly. for example, usually the product people don't know how flow X is really easy to restructure like Y and solve the same problem. kind of related, but pushing all the speccing responsibility to product is also kind of boring for me as an IC.

[Ididntdothis]

Yes, people have to work together and all roles have something important to contribute. I have been in plenty of situations where product managers and users tried to solve a problem and I could guide the discussion towards solutions that made sense development wise and also satisfied the users. Having customers or product people defining solutions alone is a surefire recipe for misdesigned systems.