> ...it corresponds to the ability of a person to convince others that they are at that level.
One note on this: as your career progresses, your ability to convince others around you that you're at a certain level goes from being unimportant to important, and then from there to essential.
After all, you need to influence others to do just about anything that involves more than yourself - and developing that power of influence is very much a skill in and of itself (see [1] for instance: it takes a lot to deliver even a simple, clear decision effectively!)