It's a bit more nuanced than that. Russia had the absolutely highest loss of life in pushing back the nazis, bar none. That is correct. Though their war machine would be rusting in the mud if it wasn't for the numerous American Jeeps and lorries they had via the Lend Lease program. Without a very mobile infantry, Stalingrad would not have been encircled so quickly, the loss of the entire 6th Army breaking the back of the Nazi eastern front push. Otoh, had Stalingrad been taken, the road to Baku would be open, the nazis would likely have their oil, Moscow would get surrounded and starved out like Leningrad, and the Soviets would have been pushed back to the Urals. Then the world would be a far different place.. ☠️