Anyone who's performed even a cursory glance at the Science-And-Data (or, alternatively, Data-And-Science) would know that there's zero evidence our "mask" usage does anything to curb the spread of this virus. If everyone was supplied with high-grade, well-maintained and consistently disinfected masks, it would likely help. But that doesn't include semi-covering your mouth with a cheap disposable mask with days' worth of accumulated bacteria and germs.
The mask thing has so obviously turned into a form of petty virtue signaling. It shows "I care," and for business owners I suppose it tells customers "We care, and you are safe here." This is anecdotal but I'm sure it's not a coincidence that my Democrat-voting/leftist friends on Facebook/Twitter are the ones who've changed their profile pictures to shots of themselves wearing masks.