It shouldn't need pointing out, but to be clear.
We rollback the restrictions, send people back to work, take some kind of half measures to protect the vulnerable but generally let the virus spread, then what happens?
Apart from the spectre of the dead lining hospitals corridors and the elderly dying in their beds en masse, workplaces start collapsing anyway as more and more people call in sick. Then we see younger people getting hit, being unable to access healthcare, and dying. Mortality goes through the roof, as various sectors shut down chaotically due to a mix of illness and fear. Transport and retail workers refuse to come in to avoid sickness and infecting their loved ones. Doctors and nurses walk out in protest. Mortality rates crest 5% and keep rising. Rubbish accumulates on the streets as anybody sane is now cooped up inside trying desperately to avoid killing themselves or their families. When the apocryphal 'herd immunity' is reached and/or a vaccine comes along, the corpses alone present a public health risk, and the cost of disinfecting workplaces and homes runs to the trillions and takes months.
There is going to be a crash no matter what we do. The question is how many people will die and how long it will go on for. Those advocating the approach above are psychopaths.