Wearing masks is common in several asian countries even before c19 was a thing and I'm not aware of anyone showing that it's causing harm at the population level. I consider that reasonable evidence that wearing them has no significant negative physiological effects.
I could see negative behavioral effects such as making people more careless because they're feeling safer. But again, effective containment in above-mentioned countries would also serve as evidence against that actually being an issue.
The hypothesis that face masks have a net negative effect is a very strong claim, before considering it we'd need some evidence that points in that direction.
I guess if you believe that's actually true, you should be advocating for doctors to stop wearing masks...
But that's not something we do, because we have enough priors that masks help that we will continue to use them.
Simple reasoning. We know that viruses can be transmitted through saliva. Covid-19 generally presents with a cough. Coughs aerosolize saliva. Wearing a mask or face covering catches most particles, and absorbs energy from all particles, so they dont travel as far. Less virus mass, and a smaller projection plume will result in less spread. Less spread results in a lower R0.
I realize that you are just enjoying being contrary here, but please try to think through your argument and ensure it isn't incorrect in itself before posting.