I'd say a Nice Incompetent person can be as demoralizing as an Awesome Jerk. The Incompetent person is making you work harder taking care of their slack while they coast and get paid equal or more salary.
And then gets the promotion since he spent the most time hanging out with the managers. Then he will hire more people like himself and there is no going back. After a while most companies are made up of mostly nice but incompetent people, and then they go under.
