Many hospitals definitely are.
The bottom line is that if we all lived in a sterile bubble we would be protected against infections. But who wants to or can live in a sterile bubble? (Not that masks are equivalent to sterile bubbles. They’re definitely not).
That’s what they seem to believe, but the problem is that the moment you inevitably ventured outside the sterile bubble you would die as quickly as the Martians in War of the Worlds. Our immune systems have to be exposed to a wide range of pathogens in order to be able to identify and kill them in the future.