You can't build a chain link fence around your house to keep mosquitos away, dammit, and that says everything about masks protecting us from micron-size viruses!
Fantastic, and very effective, mental imagery ......
But viruses don't have wings, and they can't fly from one person or place to another like mosquitos do. They hitch a ride on the droplets infected people produce when they exhale, talk, sneeze, sing, shout, etc. Droplets are pretty small, but they are way bigger than micron-size or you wouldn't be able to see them in your headlights when you drive on a foggy night.
Quality masks can impede virus transmission even if the actual virus is smaller than the pores of a mask. No one is saying they offer 100% guarantees ... they only skew the odds in your favor ... your odds and the odds of a less healthy person you may infect. The "experts" we love to hate also do not brag much on the cheapo cloth masks available at your local gas station convenience store ... the ones with designs of your choice. But the multi-ply paper KN95 masks available in such hard-to-find places as Amazon do offer less-than-100%-but still great odds.
For those who are sure they are not susceptible to COVID, or who know they will only feel mild symptoms for a few days, or who will never be near any fellow Humans who are not so fortunate ... celebrate your good luck.