Explanation
The losses of Germany on the eastern front are widely believed to be the most significant factor in defeating Nazi Germany and the USSR won the battle of Berlin, the final battle before the German capitulation. Thus Europe widely believed (for a good reason) that the USSR was the main contributor in defeating Germany. With the cold war the perception of the USSR became a lot worse in western countries like France and with increasing anti-USSR sentiment the view flipped to viewing the USA as the deciding factor. The USSR (and the Russian Federation today, even if its government is very anti USSR) viewed itself as the most important force in defeating Germany, especially because the USSR had the biggest amount of deaths. It is worth noting that the USSR was at least commercially allied with Nazi Germany until June 22, 1941 and there was an agreement between the nations on which parts of Europe each could invade and which where reserved for the other.
Even though USSR has some blame for WW2 starting (Molotov-Ribbentrop and its follow-up), I'm sure Germany did the most for it.
That pact short-circuited the Anti-Comintern Pact with Japan and is the first thing every WW2 nerd cites in trying to figure out how Hitler could've won the war. It was also a tactic to placate Britain and France that either resulted in, or proved unnecessary by, the Phoney War. Fall Weiss was already finalized to commence before September 1. Molotov-Ribbentrop was done in August.
Taking that pact out of the context in which it was made just seems odd.
Or maybe not because I know the Hearts of Irons games portray it (or did) with an 'unholy alliance' option. The games tend to give Nazi Germany massive penalties for not doing it, so the vidya brained think it is what enabled Germany to invade the USSR and/or start WW2. They're fun games when you know how they play with historical events, and brain breaking if you try to learn history from them.
"Molotov-Ribbentrop was meant to placate Britain and France"
Fucking what.
Poland had seized land in Czechoslovakia with Germany, and tye USSR had been rebuffed from alliance with most western powers already (despite going as far as preventing the Spanish Republic from collectivizing land in an effort to make them happy).
If the USSR holds blame for the start, so does the UK and France.