Ignoring the political question for the moment - it would likely reduce/delay the spread of the virus and break many infection chains that would have otherwise formed. While it is true that pretty much everyone is going to get infected at some point before a workable vaccine is made, the point is to reduce the infection *rate* to something our medical system can handle. As several people have pointed out - we actually have less ICU beds per 1000 people than Italy does, and look at how well that worked out for Italy.
That would be the reason. We’ve been slowly working to that point. Would not be surprised if it happened this week sometime.
But it does not eliminate the virus from existence, meaning that we are all right back where we are now within a few weeks or months once again. What's the point?
The US has 34.7 ICU beds per 100,000 people.
Italy has 12.5.
And I should have noted it would be local or state orders. Not nationwide.