It is true. Masks aren't very effective against preventing somebody from getting the virus. Even small changes in the R0 of a virus can have significant affect on the number of people who become infected, though. If everybody wearing masks only lessened an individual's chances of getting infected by a mere 10% (a number I pulled out of my ass), by 10 generations in you could effectively have half the number of cases. Why do you think that red states have almost exclusively filled the top 10 slots for the most cases (and deaths) per capita since June of 2020? All else being equal, it should be the other way around! Blue states have much higher population density, after all. Barring any other glaring factors, I would say this is a clear indication that masks ARE effective in preventing the spread of COVID, even if they only decrease an individual's chances of getting it only slightly.
