I think you could also apply this to software developers or other professionals where there are relatively few who can distinguish between the engineering, science, craft or ignorance of the profession.
There are good managers and management theory as there are good warriors and war theory. Not the same but have some similarities. The average general couldn’t win a complex war. Many skills are needed beyond the specific studies you have (e.g. MBA).
I agree with you that management is a placeholder that hides the ignorance behind a title. This doesn’t mean there aren’t people who have merit and strong background in management.