Unfortunately that doesn't work so well for a disease whose main source of risk to each person is the behaviour of other people.

On a different time scale it does. It’s selecting against groups/societies that reward, value or permit the kinds of behaviours and belief systems that allow such doggedly wilful ignorance to flourish.

Sorry, that doesn't work when most groups/societies are heterogeneous in ideals. Even most people being reasonable isn't enough when the behavior of the few who aren't must be tolerated in the name of freedom. So natural selection alone won't actually improve anything.

Social Darwinism, alive and well on HN...

This is actual Darwinism.