And please enlighten me on where the resources come from and how they are allocated. Do the coal/oil/gas buried deep under earth dig themselves out or the cattle/pigs/chickens will automagically grow and serve themselves on our dinner table? Command economies can only work spontaneously. The Nazi and the USSR both did have made spectacular achievements over the course of their existence. But is the process sustainable? No. That was why they both failed eventually.

The US did not become the arsenal of democracies by centralizing all the industries during the second World War. The private industries involved a lot. You can say that paved way for the future military-industrial complex. Even the secretive Manhattan project had a number of corporate partners.