I’m going to have to go watch the movie again, but I don’t recall any message that the state created (or failed to stop) the “idiotization” of the populace.

The overarching message seemed to blame rampant consumerism, not evolutionary pressure.

IIRC, the movie had no eugenics component. You appear to be conflating the concept of “darwinism” (natural selection) with the concept of “eugenics”.

The concept of “reproductive rights” allows for individuals to make their own selections for themselves and their offspirng; those choices do not constitute “eugenics” until they are imposed in another.

If the state is not applying selective pressure, it is not eugenics.

This is kinda how igloos work. They hold the heat from the ground below and the occupants inside. The interior is cold, but not nearly as cold as the sub-zero temperatures outside.