Ignore that junk scientist:
1. You can’t breathe easily through common mask fabric, so you inhale and exhale around the edges of the mask. (That’s why glasses fog up.) Thus, the same germs that you might sneeze out are being steadily breathed out into whatever space you are sharing.
2. The fabric itself is too coarse to trap viruses.
3. Because you cannot easily breathe through the fabric, your body has to work harder to obtain given amounts of oxygen, and you are inhaling some stale mask air as you breathe. People can get used to this, just as they can get used to working in 100 degree heat; but the body is still having to work harder to get oxygen.
Increasingly, savvy folks wear the top of their mask just below their nose.
Mothers have shown their kids out and about how to wear the masks thusly and not be social outcasts for not wearing a mask