Well it's not only that, if you overwhelm your healthcare system you're going to end up with excess deaths even if the same number of people get the virus in the end. Also, we've learned some mitigation techniques over the last few months (like steroids in late stage treatment) which means that the idea that 'everyone will get it eventually' just isn't relevant - its likely that our survival rate will go up over time even without a proper vaccine.
Whether this is an issue for Sweden should be clear from the death rate among the infected, but that data isn't mentioned in the article. I assume that figure is difficult to calculate without a precise/consistent case count for multiple countries.
Ironically, medical researchers wouldn't have learned those mitigation techniques (like Dexamethasone) without a large population of patients to use as experimental subjects. In other words, if we succeed in slowing down the spread (which would be a good thing) then medical research into treatments and vaccines will also slow down.
It would take longer to complete the vaccine phase 3 clinical trials. We need to see that the vaccinated group has a significantly lower risk of infection than the control group. But if the disease spread is already slow due to other measures then we need either more time to be sure whether the vaccine really works.
