A lot of experts have given the main reason which is the lack of hospital beds and ventilators. For example, let's say New York City has say 15,000 hospital beds and 2,000 ventilators. Say that everyone but high risk people can keep congregating in all kinds of close quarter manners every day and the numbers spike like in Italy except with crowded NYC there are now 100,000 cases. Experts say that 20% or 20,000 people will have serious breathing issues, colds, fevers, and there would not be enough hospital beds nor ventilators and a lot of people will did because of not getting the needed care. Without good care the people get pneumonia which is what kills most people in these situations. Most of the people that died of Spanish Flu died of pneumonia as a consequence of the virus wrecking their lungs and giving a breeding ground for either bacterial or viral pnuemonia.
That is what the healthcare experts are worried about. Have you heard experts saying this?
And general herding mentality of letting people mingle will make many of the healthcare workers sick.