I find your lack of faith disturbing: In the Company of Friends:
That said, I'll also say this: while the number of horrible screenwriters outdistances the number of horrible executives, the number of outstanding writers also exceeds the number of outstanding executives. It's extremely difficult to be a great screenwriter (or so they tell me). But it's damn near impossible to be a great executive. The system doesn't allow for it. Human nature doesn't allow for it.
Because to be a great executive you have to be able to do...nothing. You have to have the security, the sensitivity, the balls, really, to read a script and say to your boss: "You know what? It's pretty fucking good the way it is."
And who the hell's gonna do that? First off, most scripts aren't pretty fucking good the way they are. Most scripts fucking suck. Most screenwriters suck. Most movie ideas suck. Most of the reasons a particular movie is getting made suck. So executives are conditioned to think EVERY script has a pretty good dash of suck. It's a good bet to make. It's like betting with the house.