Or at least there was a reason we’ve been hearing this stuff all these decades.

Yes, and that reason is Franz Halder.

Franz Halder (30 June 1884 – 2 April 1972) was a German general and the chief of staff of the Army High Command (OKH) in Nazi Germany from 1938 until September 1942. During World War II, he directed the planning and implementation of Operation Barbarossa, the 1941 invasion of the Soviet Union. Halder became instrumental in the radicalisation of warfare on the Eastern Front. He had his staff draft both the Commissar Order (issued on 6 June 1941) and the Barbarossa Decree (signed on 13 May 1941) that allowed German soldiers to execute Soviet citizens for any reason without fear of later prosecution, leading to numerous war crimes and atrocities during the campaign. After the war, he had a decisive role in the development of the myth of the clean Wehrmacht.

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Halder denied any knowledge of the regime's atrocities and claimed to be outside the decision-making process; he was found not guilty.[50]

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As the Cold War progressed, the military intelligence provided by the German section of the US Army Historical Division became increasingly important to the Americans.[55] Halder oversaw the German section of the research program which became known as the "Halder Group".[56] His group produced over 2,500 major historical manuscripts from over 700 distinct German authors detailing World War II.[51] Halder used the group to reinvent war-time history using truth, half-truth, distortion and lies.[52] He set up a "control group" of trusted former Nazi officers who vetted all the manuscripts and, if necessary, required authors to change their content.[57] Halder's deputy in the group was Adolf Heusinger who was also working for the Gehlen Organization, the United States military intelligence organisation in Germany.[58] Halder expected to be addressed as "General" by the writing teams and behaved as their commanding officer while dealing with their manuscripts.[59] His aim was to exonerate German army personnel from the atrocities they had committed.[60]

tl;dr: US employed one of the top Nazis to rewrite history.