I think the key is compromize and risk reduction. Sick people should stay home, mask if they need to go out, & be aware of what signs of infection are.
Its true social distancing is the only “100% effective” way to not get sick. But its kind of like abstinence-- most people are not going to do the “100% safe” thing, but they will take measures to make bad outcomes less likely. Which the cdc recognizes and has adjusted covid reccomendations to reflect what is most benificial for people as a whole (stay home if sick, but no need to isolate yourself from everyone).
Perfection is the enemy of the good and all that jazz.