This reasoning is implicit in the apologists for our early pandemic public health incompetence, but it's incredible to see it concretely articulated.

How do you add absence of high-quality, narrow evidence for effectiveness + strong prior for effectiveness + ~zero-cost intervention and land at "don't recommend cloth face covering"?

All the other examples you gave fail one of these criteria: there's no prior suggesting that Crystal healing is valuable, HCQ has side effects and presents costs/supply chain challenges that _cloth_ doesn't, etc.

An example from the other side is vitamin D: there's been enough weak evidence that anyone scientifically literate has been keeping an eye on their vitamin D since the early pandemic, given that: there's moderate evidence it's protective + there's a high chance you're deficient anyway + D toxicity is pretty hard to achieve.