The idea that any project manager can be all that is so dangerously optimistic. And yes, I realize there exists some PM somewhere who proves it is possible to be a good project manager. But the existence of an outlier does not move the bell curve, it's part of the bell curve. Most PMs need to be taught to rely on their devs and product owners so they stop screwing up projects themselves.
There is nothing so dangerous as a bad manager, especially a manager who thinks, "I've got this....". And there are so many bad managers. Scrum helps mitigate this by spreading the responsibility around to the people most likely to get it, not by tossing rules at a team.