It ought to be remembered that the purpose of the “collaboration” is to maximize the number of pages produced, and when he got paid by the page Kirby had a practical interest in this system himself. What occurs to me is that most of the collaborating takes place after the work has left Kirby’s hands. As I understand the process, Lee and Kirby would discuss the basic plot orally, Kirby would pencil the entire story by himself, then hand it in for inking and writing and lettering the captions and dialog. As such Kirby is in the position of the director of a silent movie who improvises the entire story from a rough scenario, if the director played all the roles himself. Stan Lee is in the position of the writer of the title cards. The caveat here is how much input Lee actually had at the plotting stage, and since that’s become a point of contention and there’s no written evidence, by now there’s no way to know. What we do know is that since Lee was the paymaster, he would have as much input on editorial direction as he wanted. Since we have a body of work that Kirby did afterwards without Lee, we can infer that input by comparing the two. On balance, however, I think we can say that on balance, creatively speaking Lee was essentially Kirby’s caddy. A caddy might provide direction and advice, but the golfer plays the game.
This doesn’t render Lee’s contribution insignificant. The bane of the comic book had always been lousy writing, against which not even an Alex Toth could prevail. As editor Lee broke this age-old curse by writing all the captions and dialog himself, or nearly so. Having Kirby and Ditko to cook up the stories allowed him to do more captions and dialog in the same way that having someone else do the inking allowed Kirby and Ditko to draw more pages. Lee could keep things light while laying it on thick, and if he spent much of his time telling you how much fun you were having, he never forgot that fun is what it was supposed to be. If you watch recordings of Johnny Carson on the old Tonight Show you see that the key to his success was his knack for communicating enthusiasm, of signaling by his reactions that the spectacle before you was the wildest thing you’d seen in your life. Stan Lee brought a similar quality to comic book writing, and I don’t know if anyone else in the business had the brass to pull it off in the same way. More to the point, he was better at it than Kirby, whose captions and dialog, while serviceable, were flat and clumsy by comparison."