It is much simpler than the author claims. As someone who grew up in the socialistic Poland, after living in the United States for 33 years, I can see clearer than others how socialistic ideas soaked minds of Americans in the past few decades. Democrats lean toward idealistic socialism; Republicans are inclined to be closer to socialistic totalitarian trends.
Mr. Packer describes in details the ideological decay of the Republican Party. But, let us ask what happened in the Democratic Party of JFK, demanding : “ask not what your country can do for you, ask what you can do for your country” that it became the Bernie Sanders’ party of never ending demands of government delivering everything at no charge.
Socialism soaking minds of Americans, both Democrats and Republicans corrupted all Americans, not only GOP as Mr. Packer claims.
My long explanation is here: https://medium.com/@hak1010/capitalism-versus-socialism-9ece51b5ff29