I don't even think it is debatable that he is the only person without which the Marvel Age would not have happened and it is debatable whether or not comics as we know them would even exist without him. Neither Kirby nor Ditko had nearly the success without Stan as they had WITH him. Stan however had great success with Kirby independent of Ditko and vice versa as well as great success with Romita, Kane, Colan, Everett.
Lee was the Man who kept a consistent unified continuity running thru all the Marvel titles something that is sorely lacking today. Yes, he was an egoist, yes, he blew his own horn. But he probably did the work of 3-4 people and shaped an empire. Kirby and Ditko and the others may have been his commanding officers but Lee was the General and all you have to do is look at the difference between the comics Marvel put out during that time and the comics that DC put out at that time to see what Stan brought to the table. Stan is the Muhammad Ali of comic books, he is simply the GOAT. A living legend.
If you want to know who really got screwed, look at how Marvel and their BOD have treated Stan, the man who they all owe the existence of their jobs to. As to the references from the Sean Howe book, I am on my 3rd read-thru. Martin Goodman would tell Stan to fire the staff and then go off on vacation. Stan said it was the worst thing he ever had to do. He took no pleasure in it. I think that the people who want to trash Stan for not giving credit to the artists do not, themselves, give Stan his due for HIS part, probably the only absolutely vital part, in creating the Marvel Universe and the MArvel Age of Comics. In other words, take away any other single person and it still would have succeeded on some level. Even without Kirby, there were others to fill the hole, perhaps not to as great a degree of success but remove Stan from the equation and this website wouldn't even exist.