You're assuming that the subordinate's feedback is sufficiently important to the business. It might not be. It might also not be important to the business if subordinates leave b/c their feedback is disregarded. I can imagine plenty of scenarios where a leader could still succeed while not giving a crap about subordinate feedback. It depends on the goals and the dynamics of the business, the leader's experience, market conditions, labor environments, etc.
> The reason you don't fluff feedback, or any information for that matter to your superiors, is described in basically every handbook on highly effective communication in organizations.
You can argue in your exit interview that you were just following handbooks.