If all beds are taken then many of those severe cases will kill people. Say mortality is 3% instead of 0.5% once hospital capacity runs out. Assume 60% need to get it before we have herd immunity. I don’t think 3% mortality without healthcare is pessimistic. Unfortunately we’ll soon find out if the disease hits Syria and similar places.
Not only that, thousands would also die from strokes and heart attacks and other things that they wouldn’t die from if hospitals weren’t full.
Hospital staff will simply quit when their job becomes a constant struggle to keep the hallways clear of corpses instead of saving people.
It’s not “0.5% dies why are we doing this?”, it’s “we do this so only 0.5% die”.
Between a 0.5% chance of dying and a 3% chance of dying I’d happily observe some measure of distancing for 12 months to get 0.5%.