Is incompetence generally more prevalent among management-level employees or non-supervisory level employees?

In my experience, incompetence among employees who held jobs at the supervisory and managerial level was the bigger problem. In fact, problems with the performance of non-supervisory employees was often the direct result of leadership failure, not an employee’s inability to do their job. Always leery of making assumptions, so I wanted to test this theory out on all you wonderful folks out there. Of course, many of you are probably thinking the answer is all too obvious, so I’m very interested in your perspectives! Thanks in advance for your time.