[jjoonathan]

Sure, but the process can become wildly unbalanced. If the engineering is enough of a limiting factor that 90% of the planned ideas never happen and the 10% remainder consists entirely of mission-critical features, then a PM doesn't have much value proposition and it makes sense to combine the engineer and PM roles (supplemented with a culture of "why are you doing that" at standups to prevent tunnel-vision).

The opposite can happen too, of course, when the engineers focus on features that nobody actually wants. I think grandparent's point was that PMs aren't always a good cure for this problem.

[guyzero]

"If the engineering is enough of a limiting factor that 90% of the planned ideas never happen"

in other words...

If the team is wildly dysfunctional, then bad things are going to happen.