This stuff is truly bizarre. The justification is getting down to some kind of "come together" thing, not having anything to do with science but rather about global conditioning to obey.
From the WHO:
Potential benefits/advantages The likely advantages of the use of masks by healthy people in the general public include:• reduced potential stigmatization of individuals wearing masks to prevent infecting others (source control) or of people caring for COVID-19 patients in non-clinical settings;• making people feel they can play a role in contributing to stopping spread of the virus;...potential social and economic benefits. Amidst the global shortage of surgical masks and PPE, encouraging the public to create their own fabric masks may promote individual enterprise and community integration. Moreover, the production of non-medical masks may offer a source of income for those able to manufacture masks within their communities.