> It simply doesn't make any sense going one way is 100% and the other is 0%
It's not 100% vs 0%. It's probably something like 70% vs 5% (Disclaimer: I'm pulling numbers out of my ass).
When someone who is sick wears a mask, they dramatically cut down on how much virus is PROPELLED OUT OF THEIR MOUTH. That's the big win. It still likely comes out their nose or is on their hands. But at least it isn't propelled with a cough or sneeze so if you wipe surfaces and avoid contact, you're probably okay. That mask protects dozens of people.
When a healthy person wears a mask, he protects only himself and the only thing he is "protecting" against is airborne droplets into his mouth. Most masks don't cover the nose and eyes which are the primary transmission routes for droplets. Most people don't breathe with their mouth open. You're probably safer simply wearing glasses, especially safety glasses. A lot of famous singers wear glasses/sunglasses all the time for exactly this reason.
A mask shortage will exacerbate these scenarios. One healthy person taking a mask away from one sick person is a TERRIBLE tradeoff.
Conceptually, I agree completely. Your conclusions are right.
Factually, perhaps you never have seen a mask such as we are discussing here. They do cover the nose. Perhaps not perfectly, but to a very large extent.
If there were an unlimited supply of surgical masks that would make sense. If you wearing a mask deprives actually sick people of wearing one then you are still worse off then not wearing one.
That maybe true but that doesn't change the fact they help you from catching it as well.
It simply doesn't make any sense going one way is 100% and the other is 0%
And what we want is to chip away at the R0 in as many ways as possible.
And that's skipping the fact people thinking they are protecting themselves are also protecting others.