Their rational model never existed

In the standard One Lesson model of decision making, human beings are replaced by ‘rational agents’ who are assumed to be members of the species Homo Economicus. Rational agents have an infinite capacity to calculate the consequences of their actions under every possible contingency. Not only that, but they can use their reasoning capacity to model the actions of other agents, taking account of the fact that the other agents are modelling them, and so on, ad infinitum. In economics jargon, this assumption is referred to as ‘common knowledge of rationality’.

Economists have  equated the  rational model and the smooth mode.  Newton smoote or Euler smooth are conditions on the grammar needed too take indefinite limits.   Rational, as they want it, really means extinguish any arbitrage moment. 

The second means you only need be asymptotically stable in the aggregate, don't deviate farther away  from an equilibrium. Smooth may  not  apply but the model still stable with the chaos bounded.  Rational becomes fractional estimate when the model has the supporting algebra,  and I think that usually becomes a sphere packing algebra.