It's not. The goal with more successful efforts like the one in Germany isn't just "flattening the curve", it's containment. Once the infection rate is low enough you have enough testing capacity to test everyone who gets sick, and all their contacts, and thus you can find and quarantine new outbreaks before they start spreading generally.

But this only works with a very low infection rate. Once your testing capacity (which is still, basically everywhere, much smaller than hospitals' ability to treat the same outbreak) is overwhelmed, you lose control and end up back where everyone else is.

People are watching this closely.