Seriously. I can find social media posts of friends in April of 2020 sewing cloth masks to donate to hospitals/medical clinics to help them backfill their mask shortages.
Yes, we used to think non-N95 masks (let alone cotton masks) wouldn't help, and then when we got more data to the contrary, we had to update this belief. That's unfortunate, but normal.
Wait, people change their beliefs in response to new data? That's unpossible!