Because you don't want to get to the point where so many people are infected that hospitals get too swamped to handle all the serious cases anymore, forcing them to set up 'death panels' to pick and choose who they can still treat and who will have to just deal with it and live or die on their own.

Covid isn't very deadly as long as you can give everybody who needs it proper care. With too many infections at the same time, when care starts being rationed, you'll start getting avoidable deaths, people dying who could've lived if given proper care.

At the peak, that scenario wasn't all that far off anymore in New York and New Jersey. It was averted in the end, but if you just dropped all restrictions and went back to life as normal, you'd be back there soon enough.

It's also the reason why much poorer countries than the US, where people can afford much less to lose a day's income, are still implementing harsh lockdowns in some cases - they know their healthcare systems would crumble very quickly, long before they ever got to the kind of infection numbers that NY or some parts of Northern Italy had at their peak.

No doubt. And it's pretty absurd to lay 200 000 deaths at Trump's door without making a reasonable estimate of how many there would've been with a less terrible president. But then, since Trump always figures he deserves credit for everything good that happens in the US even when he contributed nothing whatsoever to it, or even when he actively tried to sabotage it, he'll just have to deal with also being held responsible for the bad.