I think you're missing the point. The point here is that some PMs feel that if they're not demanding changes, they are not necessary / not doing their job / etc. If there's nothing wrong with the completed work, such a PM will demand unnecessary changes, in order to justify themselves.

The duck is a passive counter to the PM's pathological behaviour: ensure there's always some easily-fixed fault, so the PM can feel like they're doing something, without forcing unnecessary high-effort changes. Since the duck is obviously bad and easily removed, it shouldn't prevent the PM from noticing real issues, or detract from fixing real issues.

If you feel the need to add ducks, the real problem is that you have a bad PM. But if you're a dev and have no good way to solve the real problem...