Historical studies did not show masks to be very useful in preventing viral infections, though they did prevent people from spreading it to others. That was why the original information from both Fauci and Redfield was that no, the general public did not need to wear masks.
Covid, however, turns out to be different. It not only infects you, it attempts to disable key parts of your immune system. Thus, an infection becomes a race. Can your immune system take out Covid before Covid takes out your immune system? It turns out that reducing the initial viral load slows the virus enough that it makes a mild outcome substantially more likely. Once the real world evidence, specific to Covid, started coming in, but Fauci and Redfield changed their recommendations to wearing masks.
It's fine to start out with a hypothesis that "masks don't work" or that "masks do work". You don't just ride the same hypothesis regardless of the facts, though; you change it according to what you find, and that's what Fauci, Redfield, and others have done. Redfield even make the seeming absurd statement that masks may be more effective than a vaccine. How can he compare masks to a vaccine? Simple. If you wear a mask, and you get a mild case, you have at least as good of immunity as someone that got a vaccine.