Much of the US refuses to wear masks. If masks only prevent the virus escaping but not entering, then it is only the selfish segment of society that is being protected.
From the 'less selfish' segment, yes, but not from each other.
But wouldn't that also protect the unselfish?
(Though I must admit, having accidentally bought a few of the valved ones early on in the pandemic, I found that the exhale valve actually meant my warm breath didn't heat the mask & my face quite as much, which was really nice for me as I suffer from hyperhidrosis - excessive facial sweating - but I stuck with using non-valved masks since I'm much less at risk than various friends and family members are.)