For the record, most tanks in WW2 were not Diesel powered, because in WW2 Diesel engine technology was not up to producing compact powerful engines that would fit in tanks. See below for videos of German tanks that killed their crews.
In any case the same things keep getting repeated, over and over again, and like the diesel-gasoline engine issue the people that parrot the same crap over and over can’t be bothered to get it right.
Perhaps the most notorious book about the incompetence of the US Army is Death Traps by Belton Cooper.
Having looked at the winning side, I thought that I would look at the losing side and show why, in the end the Germans strategy comes down to “how to do it the wrong way.”
Germany’s design strategy was rather different from the evolutionary development strategy pursued by it’s enemies. The Wermacht started the war with tanks that, while small were adequate for the jobs they called upon to do.
The M6 is one of those military options that the US Army pursued and then dropped. Through 1940 and the beginning of the war the US Army initiated these various armored vehicle and self propelled gun project as stopgaps and in response to evolving doctrine. As the war progressed and these various vehicles proved to be redundant, the programs were reduced to a barely sustained level and then canceled altogether. So if the question is ever asked why the US didn’t design a heavy tank, the answer is that they did. Then the Armored forces decided that the gains were not worth the resources.