On the other hand, with social distancing and masks, herd immunity comes at a lower level, even if mask-wearers still suffer >1 R0. So vastly fewer people die.

On the other hand, with social distancing and masks, herd immunity comes at a lower level, even if mask-wearers still suffer >1 R0. So vastly fewer people die. Simplistically, we don't want to lockdown or distance until we get to whatever that herd immunity level is. And then, a bit past that level, we might want to lockdown hard and then ease up to a steady-state lockdown, and then hold it there until the disease has passed. The reason we'd lockdown hard and ease up is because, well, a continuity argument -- more lives are saved if you do a week of hard lockdown when 1000000 people are infected than if you wait until 10 cases remain.