I would describe it as the "conventional wisdom" account of how populism functions e.g. the Great Depression is described as a necessary context for Hitler's popularism to be effective i.e. economic grievance fuels anti-establishment / anti-elite narratives. You get the Occupy Wallstreet movement after a crash/recession, not during a boom.

Yes. It appears that Manuel Funke, Moritz Schularick and Christoph Trebesch may not have been as conscientious as they could have been about reviewing prior literature.