‘Pure Marxist BS.’
Not pure BS.
The battle of kursk makes the D-Day landings look like a minor skirmish. I don’t think allied forces would’ve landed on that fateful June day if there had been no eastern front to exhaust and dilute the nazi forces.
The Soviets were defending their homeland, as were the Brits and the French. Yes, they went into Europe, sometimes outside their borders, but only because that's where the enemy happened to be. They were trying to vanquish Germany so it would no longer threaten them directly.
America wasn't sending her soldiers across the Atlantic ocean to fight to protect our homeland directly, because we weren't in danger of being invaded by Germany. We just went, as Allies, to help Britain, France, and the Soviets, push Germany back to defeat, and free those who had been, or were under threat of being, subjugated by the Third Reich.