First, no one is scoffing. Second, which role is essential and which is replaceable? Steve Wozniak created computers and Steve Jobs sold them. There are ten salesmen for each person able to create something worth selling.
> If this were simple, there would be many Apples run by many "promoters." Instead there is only one.
Yes -- only one Apple, and only one Intel, and only one AMD, and only one Blackberry, and only one Tesla, and only one IBM, and only one Android. Shall I go on listing all the things there is only one of?
In fact, that's a perfect place for a salesman. Steve Jobs proves it -- he didn't design the products that Apple sold, he sold them to the public.
Henry Ford didn't invent or design cars, he sold them. Thomas J. Watson didn't invent the computer, he sold computers. James McNerney Jr. (Boeing chairman) isn't an aerodynamic engineer, he sells airplanes to eager customers.
The reason for this reverence for salesmen is because of a peculiarity of American history and because of some deplorable defects in our educational system. It's because Americans think Willy Loman was the hero in "Death of a Salesman".
He contributed style and color choices to the designs of others. To quote you, "You're way, way oversimplifying things in an intellectually dishonest way."
> His role wasn't, as you say, to be handed products defined and designed by other people and figure out how to sell them.
No, he decided what color and shape the final product would have. But he could not create the technology, he could only change its external appearance.
> But I don't see why people work backwards from that and say he was only a brilliant marketer.
That's easy to answer -- name the product that Jobs designed, that someone else packaged for him.
Don't take my word for this -- read the Jobs biography (http://en.wikipedia.org/wiki/Steve_Jobs_(book)), which ultimately agrees with my view, describes Jobs as a clinical narcissist, perpetually insecure about what he didn't know, and always on the creative sidelines trying to exaggerate his role in the final product.