Warniing!
Opinion Follows, read at your own risk!
At the very least ..
..when you say 'the Russians' you refer to Stalin.
One man, one personal agenda, ego driven and very resistant to advisors,
..reluctant to change even when his ideas were blatantly proven wrong.
After the purges there weren't many who would tell him anything he did not want to hear.
From what I have learned over the years he probably chafed quite a bit feeling inferior to Hitler,
..watching Hitler just run amok over France probably had Stalin thinking he could do that, too.
I would bet he thought he could stomp the Germans hard once they got involved in Britain and just roll them up from the back.
Unfortunately for that plan, the British in the person of Winston Churchill,
(who actually did listen and act on advice from those who knew more than he did)
(most of the time

..did have an idea that they were in a fight for survival
..managing to capitalize on Hitler's mistakes along with enlisting the aid of everyone they could.
With Germany .. anytime someone says 'the Germans' they refer to Hitler ..
..altho his Commanders had a bit more leeway early on,
..it was still one man's agenda, ego, and personality.
He screwed up by the numbers so badly so many times there are times I truly wonder if he wasn't working for the allies.
He sure wasn't trying to 'win' his war in a logical, proficient, military manner.
Just my 2 copper.
-Frank aka GE