Testing helps a lot more than that, because it helps you catch infected people before they spread it further. This was a key factor in China and South Korea getting the disease under control.
It helps you know that infected people exist, but in a "free" state, that's all. Unless you both require verifiable ID and have the power to quarantine someone against her will, you haven't "caught" anybody.
Of course, then people will say "we were just lucky" or the threat was never real.
But in terms of actual germ control, I would like to see more focus on shifting the culture to one of higher levels of germ control permanently.
But I don't need convincing. I already know this stuff is serious and makes a difference because of my medical situation.