But there are other facts that permitted the Nazis to kill so many Russian soldiers and civilians chief among them Stalin's incompetence in running the war and murdering most of Russia's best officers a few years before the war. Stalin still didn't react to the German invasion until weeks after the initial attack. And millions of ill-trained Russian troops were slaughtered through inept strategy and merciless punishment by the NKVD. Still Russia's role in defeating the Nazis has been underplayed for decades.
Remember though that Britain and the U.S were also fighting the Germans AND the Japanese on two other fronts plus the sea warfare. Additionally we gave or loaned Russian millions in supplies and equipment. Russia also likes to portray itself as the sole heroes of WWII, however that is not totally accurate. But we should give credit where credit is due. They did kill most of the Germans.