In his book published in 1969, Laurence Peter proposes the Peter Principle: "In a hierarchy, every employee tends to rise to his level of incompetence.”
Many promotion decisions are beyond logic, such as promoting an engineer to a manager because they are an excellent engineer. The decision is made based on the employee’s performance in an engineering role, but engineering and management are completely different sets of skills and should be treated as such.
Engineering skills involve technical and mechanical skills, whereas management skills involve a lot of soft skills such as interpersonal, communication and delegation skills. They are worlds apart.
Of course, it is possible for a technical professional such as an engineer to acquire these skills, but adequate training and support need to be provided. Also the professional needs to have time to incorporate these new skills into their repertoire, taking into account the magnitude of the change.
Imagine spending years upon years giving computers specific commands and waiting for concrete results to be returned; then trying to change communication styles to do the same thing with humans, who respond in different ways to commands. This is a tough transition.
Employees should be promoted to higher positions, not based on their current performance alone, but also on their ability to perform in their new role along with their aptitude for professional development.