[nradov]

There is no reliable evidence that the masks most people used were effective. For the most part it was a waste. The notion that we should do something just because it might help is ridiculous. I'm certainly not willing to put up with that nonsense.

https://doi.org/10.1002/14651858.CD006207.pub6

[defrost]

The conclusion to that paper is telling:

    The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions. 

aka: We can't decide whether masks (or other interventions, including hand washing, etc) worked as all the examples we looked at were a clusterfuck of many people pulling in opposite directions preventing any clear conclusion from being drawn.

     Harms associated with physical interventions were under‐investigated.

Sufficient clean data is lacking.

Further:

    There is a need for large, well‐designed RCTs addressing the effectiveness of many of these interventions in multiple settings and populations, as well as the impact of adherence on effectiveness, especially in those most at risk 

ie. They don't believe the matter is settled by any means.

The most interesting part is the selection criteria.

Looking at the section Characteristics of included studies it appears some effort was made to trawl two decades of global trials in order to find those least likely to have any good conclusion.

Many of the trials look at the effectiveness of low level encouragement to try an intervention at a time and low location with relatively low risks, leading to intermittent uptake and noisy data.

[RandomLensman]

Do you reject most medical treatment then as it usually only has some probably of success (it might work, but need not)? What about seat belts? Presumably your position is a lot more nuance than your wording?

[Tao3300]

I think you just missed the nuance.

GP said "the masks most people wore", which is not to say all masks, but rather suggesting that the majority of masks that real people were really using and how they used them amounted to nothing.

> What about seat belts?

If it helps (though I never met an analogy that wasn't rotten on the inside once dissected in debate) an inadequate or improperly worn seatbelt can be more dangerous.