You're not wrong about incentives, but an org where PMs have fully segregated duties from devs is exactly the organizational context that breeds disconnected engineers juicing their burndown chart. I mean what do you think is the predictable outcome from a PM whose main job is googling his competitors and stuffing high fantasy JIRA tickets in the engineering backlog based on his mystic customer divinations. Neither of these people has made contact with a customer in their lifetime.
however that's not a [dys]function of simply having a product org, that's a problem with poorly qualified, poorly performing employee. or a poorly describe job function. usually with the boss/management similarly poorly equipped since they don't see past the metrics they themselves (usually) have established for "success".
i think like the GP, you are conflating poor execution of the concept/model with the deficiencies of the model itself. one does perhaps encourage the other, however it doesn't need to be that way and isn't inherent.
i mean, in 3 words, "haters gonna hate". meaning that people that are poor at execution are going to be poor at it no matter the model in which they are embedded. but when you do have a good product team, the product org (as a model) gives them the ability to maximize a less than ideal engineering team. of course, still there's many a slip twixt cup and lip.
