The idea that a specific proof 'creates' the equivalence between sensitivities based on the fixed point and those of Karush-Kuhn-Tucker seems to me an overly simplified conception. History teaches us that mathematical principles and their underlying relationships, such as this equivalence, preexist their discovery and formalization; a proof merely reveals or demonstrates them. The historical precedent is clear: Newton did not 'create' gravity, he explained it; similarly, this proof does not create the equivalence, it formally establishes it and makes it usable under specific conditions, such as convexity or differentiability. Without these rigorous conditions, the equivalence can collapse, as seen in financial markets where an exogenous shock, such as an unforeseen liquidity crisis, can invalidate models calibrated on theoretical proofs. The record shows that what appears to be 'created' in theory is often a preexisting truth brought to light, with limitations of application.