Because it is the same media that fawned over Hitler as a man with good manners, vision for Germany, a lady's man, a fashionable dresser, a man who loved dogs and a health conscious man who recognized the danger of tobacco smoking. This type of fawning coverage didn't die down much until
Crystal Night, 9-10 November 1938, didn't die down a lot until Hitler's brutal invasion of Poland the following year, and didn't die down completely until his invasion of Russia two years later.
It was then, and only then, that the plight of the Jews and others in Europe began to command significant mainstream media attention.
BINGO! The Commies in the US thought he was one of them, fawned on him, not understanding just how evil he was. Then he attacks the Commie-land, then all bets were off.