No? The point is that there were "obvious" mechanisms for why it should be true, but then non-obvious mechanisms which ended up making it false. Without data we can't know the impact of those non-obvious mechanisms.

Yes, there is some truth to that, but there are different forms of obvious. The effects a food or drug may have on the body after being ingested are never truly obvious. The internal workings of the body of an animal are extremely, extremely complex; there are so many factors involved. This is why there's never been any sort of consensus on nutrition.

Meanwhile, if someone were to say "it's obvious that wearing nitrile gloves and properly disposing of them reduces the chance of viruses coming into contact with your bare hands", true, this is not 100% obvious. There are potential failure modes here, there could be some unknown unknowns. But in general, this seems pretty obvious. We've been using gloves for these purposes for millennia. We have no reason to think they're ineffective at preventing harmful particles from touching your bare hands.

The same is true of a face mask. If a virus is likely to infect you by entering your nose or mouth, then covering your nose and mouth is likely to reduce the chance of infection from the virus. This has again been known for millennia. It's the reason why Asian countries have been wearing face masks since the start of the COVID-19 news. It's why every national and global health organization is now advising that people should start wearing masks. And it's evidence that the Surgeon General of the United States very likely knowingly lied to the US public, possibly causing unnecessary deaths.

> "it's obvious that wearing nitrile gloves and properly disposing of them reduces the chance of viruses coming into contact with your bare hands", true, this is not 100% obvious.

I think this is a little bit unfair of an analogy because the question is not really "does it reduce virus particles from coming into contact with your bare hands", the question is really "does it reduce your chances of getting/spreading the virus" which is not so straightforward.

> If a virus is likely to infect you by entering your nose or mouth, then covering your nose and mouth is likely to reduce the chance of infection from the virus.

That mechanism does seem obvious but what if the reduction is only a few percentage points or something? Consider how the virus particles could potentially pass right through many coverings, and they do nothing for your eyes or other bodily openings. It could be totally counteracted by, for example, having virus particles trapped in a moist space in front of your face for hours at a time. I have no idea if that's true but I'm just trying to say, there are plausible mechanisms that could negate the effectiveness of masks outside healthcare settings.

> It's the reason why Asian countries have been wearing face masks since the start of the COVID-19 news.

Asian countries have acquired a culture of wearing face masks based around beliefs, not data. That is not a demonstration of face masks being effective, unless you are trying to say that since implementing such a culture we've seen a reduction in viral infections there. That would indeed be a good argument for masks.

And keep in mind that mask-wearing in Asian countries didn't begin with COVID-19. It has been popular since the SARS outbreak at least.