If they don’t restrict oxygen, you are not wearing it properly. The whole point of a mask is to restrict intake and outtake of air.
For N95 masks, the point is to FILTER air; NOT “restrict” it.
For regular surgical masks and the like, it’s not even doing much of that. What it’s actually doing is filtering respiratory droplets, which are how SARS-CoV-2 primarily spreads. In open air, SARS-CoV-2 (like all viruses) experiences rapid protein deformation, rending it inert and non-infectious. For it to spread, it requires droplets of liquid - such as saliva - which a mask helps trap.
Masks reduce both the volume and range of the respiratory droplets that enable transmission of SARS-CoV-2, which substantially reduces the risk of transmission for those nearby an infected person.
Stick to what your betters are saying, AppyPappy! Today, they are telling you masks do NOT restrict oxygen and that said oxygen exiting or entering the mask is impervious to C-19 aerosol contamination. Tomorrow, if they tell you otherwise believe them! They’ve got this.—FRearpers, Inc.