Problem is until we reach "herd immunity" it will overwhelm the healthcare system and many people die unneccessarily due to degrading quality of treatment.
Let's say that it's only 0.2% risk of death without a ventilator for the general population (based on https://www.latimes.com/california/story/2020-03-11/covid-19...). Let's say in the USA that we're talking 150M infected people who aren't high risk (65% or ~200M of the population is between 15-65). That's 300,000 people who will need ventilators (potentially for multiple weeks -- https://www.uchicagomedicine.org/forefront/prevention-and-sc...).
"The latest study available estimates there are about 62,000 ventilators in hospitals nationwide. That figure is seven years old — so the actual number could be higher." -- https://www.npr.org/sections/health-shots/2020/03/14/8156756...
So yeah, you don't want all of those infections happening the same month or else hundreds of thousands of people will die.