I agree that testing is the way to go, but there are only so many tests you can do (physically, depending on supplies), so you really have to prioritize those who have actual symptoms.
On the surface it makes sense that masks wouldn't help. The more I think about it I come to a different conclusion.
Masks do cut down water vapor being absorbed through the nose/mouth. It's not 100% but this isn't anthrax where a tiny droplet could kill everyone. Many people would use it improperly but simple public service announment instruction could solve that issue. Instead they use valuable public serivce announment time to tell everyone not to use a mask. I believe they do this to get people to not buy masks because they are afraid of supply issues. If we had a huge supply of masks people would be encouraged because it would cut down on spreading.