I think this is the point about slowing the spread though. It's about protecting the vulnerable populations by not flooding the environment with disease. It's a matter of public health. Sweden's numbers are bad because they just let things roll, didn't protect people, and a lot of people have died that didn't have to.
We're on our way here too. Nashville just rolled back to Phase 2 because people couldn't stay out of the bars. You can say, well, let the younger people get it and get towards herd immunity, but those people walk around in society. They live in buildings with vulnerable people, go to the grocery store with them, work with them, and generally spread the disease into environments where people who need to be protected maybe can't protect themselves. This is especially an issue for minority communities where there is a larger percentage of poverty and fewer healthy people who can assist.
This uptick in younger populations getting the virus will lead to upticks in older populations getting sick and an increase in mortality in 4-6 weeks.
I think things do need to be open to a certain degree. It needs to be regional based on current conditions (e.g. Phoenix and Boseman, Montana should be treated differently), but to say we should just let everybody get it and the geezers need to stay home ignores the reality of vulnerable people.