In any technical project requiring more than a few people a small number of the people assigned will gradually emerge as the technical leads, the alpha geeks. This isn't by designation. It's a meritocracy in action. Even though there is no official process, the results are fairly objective. Lower levels of management retain some vestiges of requiring technical competence but, the higher you go, the more the results of who gets promoted are governed by how well an individual shmoozes, kisses fanny, acts as their own PR and other subjective qualities. It is very difficult for higher management to differentiate between an easy project and a competent manager or a hard project and an incompetent manager.
If the above situation isn't enough to keep good engineers from becoming engineering managers, the reward you get for moving to the management track is technical obsolescence. The only thing you become qualified to do is be a manager. In larger companies the only thing you may be qualified to do is be a manager at that company since the bulk of you time is consumed by navigating the arcane bureaucracy that you are part of.