What kind of Russian propaganda is this? None of the allies could win alone

This is 100% correct. Also, anybody who actually knows the history in detail knows that America concentrated most of their fighting forces in the Pacific theatre and served more as support in the European theatre.

Russian propaganda?

The chest-beating confidence of people chiming in on Internet is appalling to me. Stop presuming you know more than other people and READ MORE BOOKS.

The strain of American Exceptionalism in the typical American historical outlook is depressing to me.

There were single battles on the Eastern Front which resulted in more casualties than the United States suffered throughout the entire war across all fronts. Look it up: Leningrad, Stalingrad, Kharkov...

The United States first seriously engaged with German forces in Tunisia in 1943. By that point, the USSR had been fighting with Germany on a massive scale for a year and a half. That was after the Battle of Stalingrad, arguably the most significant turning point in the entire war.

The Germans deployed roughly 50 divisions on the Western Front. Roughly 150 divisions were on the Eastern Front.

The United States contributed materiel and strategic bombing, but did not do the lion's share of the fighting, killing, or dying.