You are technically correct. I would restate it thus: "Germany could have defeated the Soviet Union very easily, if they focused on taking Moscow." Hitler, being Hitler, was incapable of such a direct and uncomplicated strategy and resisted it for several months over the protests of his best generals. By starting the Barabrossa campaign late, and by repeatedly overruling his generals Hitler ensured that his "window" for success at Moscow was vanishingly small. So IMHO, he lost in June, 1941.
Hitler probably also thought that as unpopular as Stalin had to be with his soldiers, it was easier to convince them to surrender...but if suddenly Stalin were replaced by a more popular figure, then the Russians would be more determined to fight against the Germans. So Hitler actually preferred to keep Stalin in power, which in hindsight, was a big mistake.