`  == Citation needed? ==  ``The idea that payments to factors of production equilibrate to their marginal productivity had been laid out early on by such as John Bates Clark and Knut Wicksell, who presented a far simpler and more robust demonstration of the principle.`` This seems like a bit of a value-statement without any verification. It's essentially saying that they were better in every desirable way then their followers. I think this needs a citation at the least.   `