anyone can easily look at current data on the subject. The data aren't being hidden, and it isn't some new concept. Masks are part of universal precautions in every US hospital for a reason, and it isn't because of some industrial mask lobby has somehow bamboozled penny-pinching executive committees to buy them for no good reason.
The old adage about hospitals being where the sick are, where the potential for infection is, was and is true. Now the non-healthcare population gets to experience an analogous risk scenario due to a pandemic. The same precautions that work WITHIN hospitals to prevent or reduce infections, shockingly work outside it.
Take 5 minutes on pubmed or the latest medrxiv and read some of the data/research that exists.
https://www.medrxiv.org/content/10.1....03.20051649v3
https://www.medrxiv.org/content/10.1....09.21256922v1
https://www.medrxiv.org/content/10.1....16.21258817v1