I have very rarely encountered a PM(any title) who lucidly communicated their value-add to the company. It is certain that, e.g., someone needs to assess the pricing of a product and how to position it in the market. But it's unclear that the vast majority of people I've worked with are performing that task - they are, to all appearances managing projects and doing secretarial coordination work (ticket munging), something experienced devs and managers can do straightforwardly up to a certain point.

I think its one of those roles that you don't need until product (project) scope is a certain point, but it's been glommed onto smaller companies as they mimic the big-corp designs. So it never quite works for those small shops. They really just need a Product Person, singular, who drives the thing forward, IMO.