Just to give an example, I have seen a few competent but unexceptional engineers become CEOs and CTOs over a few short years in a growing company, while other, better engineers never advanced beyond a team lead, if that.
Being a manager is a radically different job from being an engineer. In fact, I think that (generalization warning!) good engineers make bad managers. Different attitudes, different personalities, different skill sets.
You know the drill - If it's worth saying, but not worth its own post (even in Discussion), then it goes here.