In my experience it most efficiently explains lower and middle managers who were internal promotions from the ranks of non-supervisory or regular staff.

In some jobs, like academia, you will run out of regular promotions and will just end up plateauing, especially in salary. The only way out of this is to become a manager of some sorts: department head, assistant manager, section head, project manager, etc. or to do a lateral transfer to a different job where you can renegotiate salary, benefits, and job description. Or in the case of true academics, supplement income with book tours, speaking fees, consulting, etc.

Some of the worst managers I’ve encountered were people who had been doing their jobs for about a decade and needed that “promotion” to management to get a raise or move away from a job they physically or emotionally couldn’t do anymore.

But bad managers are a bell curve with MBAs and career management types on one end and “Bob, who finally got that promotion” on the other.