I've never heard populism described as a message "delivery system" in quite the way you've used it. I find this article very informative and interesting, but I have always thought of populism as more of a pure political philosophy--like fascism, democracy, communism, monarchism, republicanism, etc.

I've been a lifelong fan of populists. I cut my political teeth on William Jennings Bryan and Charles Lindbergh (Sr., and Jr., ...but especially junior.) I see populism as the more sensible of the reactions against monopolism (the other being progressivism..i.e. socialism)...here in the USA that would be specifically against the enormous power and influence of the oil industry led by the Rockefeller empire.

The monopolism of the early 20th century which (I believe) came to thoroughly dominate the republicanism of our founders, is, IMO, a nearly equivalent evil to totalitarian fascism and/or totalitarian communism. It has morphed slightly into what we now often hear called oligarchy or "crony capitalism" now, but the energy basis of our economy still drives American politics--especially our "science" (or what passes as acceptable science,) academia more generally, and our foreign policy.

Populism..i.e. the idea that government should serve the popular needs of the greatest number of people... is the antithesis to our current system, and it is a MUST USE rhetoric for anyone seeking high office in any but the most left-wing areas of the nation. I still have my doubts that DJT is a real populist. Most astute politicians run populist and "serve" statist.