It's actually quite gross. A moist cloth/paper mask that has stuff growing in it.
Your mouth is a filth hole. Mine too. That is why when kids bite in each other in kindergarten and it breaks the skin, there is concern: https://newsinhealth.nih.gov/2019/05/mouth-microbes
Folks wearing these masks are spraying that crap into some fabric, or paper, and then breathing through it, hours and hours or even days on in.
A doctor replaces that mask continually.
A doctor replaces that mask between patients.
How often do you see the mask wearers change them out?
And besides that, the doctor is concerned with a whole slew of bacteria that a mask can actually somewhat filter. But a virus that is .1 um, with the better masks and layered only getting down to .3 um. How does that work? Obvious, it don't.
This isn't an issue of “following the science” which very few actually have to back themselves up with.
It's an issue of how it makes people feel!
Since people want to feel in control, they want to pretend like they can “do something,” ideas like a mask ring really loud inside their head. The mask gives people something they can do, they can cling too. It makes them feel empowered. It's the same as when Obama was asked about his energy policy and he replied: https://www.youtube.com/watch?v=DnhQ9pHv8lY
Nailed it!