The vast majority of face masks that consumers were are ill fitting and don't protect anyone really. 10% is trash. They don't protect themselves or others.
If condoms and other birth control methods were only 10% effective, no one would use them because they would be worthless. If pain medications were only 10% effective there would be no market for them.
Face masks are fine for a virus that spreads through larger droplets. They are not for virions in the air. Covid was thought to be mostly spread through larger droplets initially, but indoor airborne spread has realistically been the largest mechanism for infection. Fauci and many other people knew that consumer grade face masks were worthless.