I hate hearing this argument. Simply because I'm living proof of the opposite: I'm not a native Swede, I immigrated here, I integrated into society by looking at its values, identifying with most of them and sharing those forward. I became a Swede and it has nothing to do with being born Nordic or into a homogeneous culture.
This hand-waving argument on why America is exceptional is really misplaced. America has issues because it has a big population and manages everything in terms of money. Money is the religion of the USA, it's the ideology of the country and when the only metric you use to gauge anything is on how much will be spent and how much return it will give in monetary terms, you end up with a deeply fractured web of perverse incentives and misplaced cooperation to juggle one metric: money.
America was built in a culture of mistrust, it came from inception and it never fought it. Distrust from centralised government, distrust in others (hence having guns, you don't trust you'll be protected from others so you need to take matters into your hands), distrust in commercial relationships, in personal relationships. It makes society feels fake and shallow, like everyone is just playing a part. There is just a lack of communal sense in everything regarding American culture, it's all about individualism and the self.
Sweden may be seen as a communal society but it's really not that simple, I like to say that Sweden is the most communal individualistic country I've been to, people still value self-reliance and individualism, while also keeping in mind a holistic view of society.
I wish Americans could see past this exceptionalism and move towards building something based on trust, it'd be a force to be reckoned with. Right now it's just a huge waste of bickering and pettiness all around, every single issue in America is amplified by this huge egoistic mindset.