A interesting read from a interesting viewpoint.
From my own view, it seems as if the entire Marvel Universe has been a constant rehashing and re-using over and over, the same stories, concepts, and characters created by Kirby and Lee between 1961 and 1968.
The last years at Marvel, Kirby, as everybody knows, kept all his new ideas to himself and did not introduce any new concepts or characters.
Lee's contribution at this same time was less than spectacular. By '72 he was promoted to publisher and was no longer involved in creating new characters or continuing on those he had a hand in creating.
B.