The Peter Principle is a well-known management theory that posits that employees that are eventually promoted to a level where they are no longer successful. Colourfully called their "level of incompetence", this is the first point past the employee's capability.
While the book, as I understand it, is somewhat tongue in cheek (more here), it certainly feels truthy. It's certainly anecdotally true when we see a manager who struggles or a CTO that clearly doesn't know how to lead a department. Someone performs quite well at a mid to mid-senior position, gets promoted then doesn't excel at their new senior position. The cause is asserted to be the change in responsibility or mastery of a skill that is now beyond the capabilities of the employee.
This idea has made strong roots in the software industry since most senior roles not longer require writing code which is the main activity of most of the entry-level to intermediate workforce. The industry as a whole is struggling with what to do with its senior engineers.
So conversely I wonder:
Are we eliminating great potential managers because they can't code?
The current natural progression in most career path is the same. Do something (Junior-Intermediate Widgeter). Do something at a senior level (Senior Widgeter). Optionally, do it even more senior (Senior Widget Architect) Becoming some kind of manager of that thing (Director of Widget Production). Then manage people who manage people who do that thing (VP Widgets).
However, once one moves past the production phase of the career path, the management path requires a different set of skills. This is evidenced by the myriad management books that start by advising you to remember "you don't do that job anymore". These new skills often involve time management, stakeholder/customer management and managing a team. These are distinct from the skills that earned the promotion in the first place.
So the status quo has us choosing from a pool of people with great production skills but possibly not the best candidates for the managerial skills. While I admit that being a great developers helps to be a great project manager, I wonder how integral it is.
Can we conceive of truly flat workplace where even though someone might manage a team but not be considered higher than the team members? If so then we might be able to evolve to a place where people can be groomed for managerial roles rather than thrust into them with a jarring change in responsibility. This would help open up the pool of candidates which is ultimately the starting point of better employees.