According to this study, with two people talking 3 meters apart and one infected, if only the non-infected person wears an ordinary surgical mask (not n95), it

According to this study, with two people talking 3 meters apart and one infected, if only the non-infected person wears an ordinary surgical mask (not n95), it increases the time to the 90% bound for infection risk from 1.5 minutes to 30 minutes. So at least in theory it's certainly not for nothing.