What's the alternative? Simply letting people die without any help? If the mortality rate is low, surely that's also because people actually are getting help?
Mortality rate aside - the point is that the medical system can't handle everyone getting sick at once, hence the need to flatten the curve. Regardless of corona, there's a shit load of stuff already going on at most hospitals and the capacity is most likely maxed out already in many places. The hospitals can't handle a huge influx of corona patients on top of that as well.
Also, the corona is not just a regular flu. For some, it might be, i.e., mild symptoms, but some people actually get really sick and I believe it's a bit more contagious too.
At least that's how I have understood it.
But I'm spending most of my time on charts and trading, so have not been able to research it in depth.