They defeated the Nazis by throwing conscripts into a meat grinder regardless of whether they even had a weapon, and by threatening to shoot them if they tried to retreat.
Enemy at the Gates is not a documentary, it’s a propaganda film. In true fact while the Soviets did have a large number of conscripts and did suffer supply issues early in the war, at no point were they sending under-equipped battalions into the front line to die for no reason, and the thing about shooting those who retreated only applied to officers who ordered a retreat without proper cause (you’ll find that every other army in World War 2 had a similar protocol).
I’m sure we’ve seen the towering number of deaths from the USSR meatgrinders
https://www.youtube.com/watch?v=DwKPFT-RioU
We still see the same “throw soldiers at it” mentality in the war in Ukraine today, Russia is just like that. Nothing particularly to do with Socialism, more Authoritarianism.
Likewise we see poorly equipped troops in Russian forces today too. Same thing different era. It’s just the mentality there.