Being a democracy, the policies of the country are inseparable from its culture and demographics. You say universal healthcare might stem the tide of cultural breakdown. But we cannot be sure the causality doesn't flow the other way. Unfortunately, it's likely a feedback loop. We have bad policy in part due to the cultural and social decline the author describes, and we have cultural and social decline in part due to bad policy. Simply proposing policy changes neglects the complex interdependencies of these things, and is why national demographics are so important in a democracy.
Part of the reason NZ is able to cohere around its policy more than the US is because everyone in NZ (to a greater degree than in the US) shares the same values and cultural identity. This is why you see similarly idyllic societies in the Scandinavian countries. High social cohesion due to shared cultural and ethnic identity. Same in Korea and Japan - although Japanese culture is a good example of some of the downsides of ethnic and cultural homogeneity as well.