I have never been able to follow the logical step between "this is pretty obviously a bad thing" and "but it's okay and everybody should shut up about it becaus

I have never been able to follow the logical step between "this is pretty obviously a bad thing" and "but it's okay and everybody should shut up about it because it was 'common knowledge' -- i.e. what we might have previously called conspiracy theories -- among some unspecified set of people who may or may not have been dismissed as tinfoil hat wearers".