The American school economic approach certainly worked in the 18th and 19th century.
We just don't live in those centuries anymore.
Increasingly world interdependence for resources and markets, too, makes our past semi-isolationism impractical.
I'm not entirely sure I know what "neo-Keynesian" economics really means, so I'll refrain from responding.
But I will submit that what our government is doing right now is NOT a terrible good example of what Keynesian econmic theory promoted as a solution to the deflationary cycle that we faced in '29 -41.
Don't get so hung on on lables that your mind shuts down.
The devil is always in the details.