Its based mostly on evidence it will benefit others, which seems to be widely agreed. It might also benefit the wearer directly. It has little downside, provided you dispose of them properly. What is it some people are getting so heated about ? It's no more an infringement of your freedom than being expected to wear clothes in public, to not drive pi**ed, etc etc. You can't have complete freedom whilst living within a society and enjoying its benefits. Consideration for others is all part of the package.
So what would those who don't want to wear a mask do about Covid ? There is plenty of evidence on the John Hopkins site of what happens when you drop your guard. Demonstrations in the US are reflected, as is - I think we can hopefully just see - the change in attitude to mask wearing. Ramadan is visible in Muslim countries. The partial re-opening in the UK is reflected in a gentle rise - showing return to life as normal is not one of the available choices. What's your better plan ?