[rualca]

I don't understand your confusion.

From day 1 it was always very clear that although protective measures such as facemasks do protect the individual from contracting the disease, their primary value is to prevent the mask wearer from spreading it.

We're talking about a disease which is known for having week-long periods where asymptomatic/presymptomatic carriers can unknowingly spread the disease.

Think about it: why do you believe surgeons wear face masks, latex gloves, wash their hands, wear lab coats, protective shoes, and do their surgeon things in sterilized rooms?