Economically it doesn't make much difference. You can either isolate people now or later. The period of isolation will be roughly the same because you have to wait for the virus to exhaust its pool of hosts (in a household). Definitely politically it makes a big difference.

Now and later make a HUGE difference economically. Time value of money. Business cash flow. Not to mention, if it turns out to be unnecessary later, later becomes never.

The scale of the problem will be so much larger because we aren’t doing a quarantine. In an exponentially growing virus, one single day makes a large difference.

True, there might also be a vaccine in the future.

Another argument is that we just need it to grow slow enough for a vaccine to be ready.