The right take is that economic models make assumptions to isolate important forces, in the same way you might assume away air resistance in some cases.
That said, we do have to be vigilant that when you assume away frictions, it can bias policy away from intervention.
They have
1. Walrasian and Marshalian Equilibrium
2. Nash Equilibrium
3. Rational Expectation Equilibrium
And it is difficult to decide which one is more nonsensical. Tough competition