>"Nash-equilibria are PPAD-hard (and communication hard) so Nash-equilibrium as a concept is bad because it's computationally difficult."

I think that's a perfectly cromulent position actually. It's a great example where the theory doesn't help when you're working with real non-homo economicus agents, and I would argue hurts if you assume that people behave (or should) behave according to those concepts.

>This is "rational" as in "rational agent" (utility-maximizing, or an agent that makes at least Pareto-optimal choices, or who plays to Nash or correlated equilibria)

...even worse. Go find me one of these perfect information people. I suppose you could collapse the stated preference and revealed preference superposition into observed preference to solve the equation.