What they do demonstrate is that masks reduce the amount of virus emitted and inhaled.
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1. Not credible. The masks leak and the fabric itself is not military grade.
2. The masks make harder to breathe, forcing users to breathe more to get the same amount of oxygen. Thus, if you are breathing germs you are breathing more of them
3. Even if the masks were somewhat effective, the positive effect is likely too small to justify inflicting masks on the entire population to prevent a disease like this that is generally lethal only for certain identifiable groups.
You are assuming things that are contradicted by many. Masks are proven to reduce in out, NOT prevent entirely. One thing I did not say was we need to wear masks safely and effectively and lay that out in detail.