I think there’s sufficient correlative data from Japan, Korea, Vietnam and Taiwan all of whom endorsed widespread mask use. Japan had no lockdowns, Korea minimal and both have a fraction of the infection rates of the U.S. Increasingly masks are seen as a factor. I don’t need to post the links. A shallow search will deliver all the research on this.
The reality is we’ve got no other defenses other than distancing and shutdowns. The latter is untenable long term. Some people won’t wear masks as a personal statement, similar to anti-vaxxing being a personal statement in response to a tiny risk of a bad outcome, no matter what the science says.
The downside of wearing one is so trivial I don’t get the resistance. Unless it’s shown that they cause infection, which seems absurd.