Afaik Sweden's government didn't have teeth to deal with covid. They did try to push legislation that would have helped, but it won't happen fast. Only war or threat of it allows martial law there. It is hard to convince people to curfew and close businesses when there is no legal base to do so.Jack will certainly chime in, but I don't think it's being dismissed as a valid concept. The problem is that no country in their right mind wanted to deal with the numbers of hospital, ICU and deaths that will occur on the way to achieving herd immunity. Also, it was not certain as to whether herd immunity will work.
It's sounding like Sweden has underestimated how long it will take to have enough people infected to achieve herd immunity.
Swedes were perhaps sold on the concept and costs of achieving herd immunity by the promise of unaffected summer holidays with countries around the world welcoming the almighty immune Swedish tourists.
Instead they have an embarrassing death toll, a long way off herd immunity and the pariah of the EU.