1) Foremost how most of the commenters are reacting to it seems to demonstrate that many of them didn't bother reading that it's about Sweden, and are acting as if it's about the US. The discussions really aren't about the article, or prompted by the article, but about assumptions and preexisting ideas. The submitter should have indicated in the submission title that this was about Sweden.

2) https://news.ycombinator.com/newsguidelines.html - Off-Topic: Most stories about politics, or crime, or sports, or celebrities, unless they're evidence of some interesting new phenomenon. Videos of pratfalls or disasters, or cute animal pictures. If they'd cover it on TV news, it's probably off-topic.

There's nothing particularly "interesting new phenomenon" about the majority of crimes being by a minority of people, even in Sweden. The specifics are important for social policy, but don't really cross this threshold.