I assume this is because our (ie. US run) entire present global financial, security, and political order sprung from WWII, and depends on maintaining this simplistic mythology.
And not because our socially-accepted history is all a pack of lies, either. Its is not. Rather, it is just that it has been over-simplified, with any sordid details that do not show favorably on this story having been removed.
One thing is for undeniably certain - Churchill, and especially those closest to him from his class and generation, took the UK from dominant global empire in 1914, to bankruptcy and also-ran status in a short span of 30-35 years.
A truly wise leader would have avoided such a fate. A stupid one is destroyed by it. An average one just survives it.
Cooper (nor any other sane person) doesn’t believe that the narrative of WW2 is a “pack of lies”. Rather, that there are pieces and parts which should be interpreted differently than how they have been. Unfortunately, this is not allowed for this one particular war.
We must believe that Hitler’s treatment of the Jews was UNIQUELY evil while the millions killed by Stalin or Mao was just “common evil”. Any other view is apostasy to the new world order.
Cooper tries to unpack why this is and what it’s ramifications are today.