The French and British were also stronger, but that didn't save them. Hitler made the fatal mistake of settling for economic goals in the Ukraine in August of 1941, rather than directing an attack on Moscow from Smolensk to finish off the Soviet State apparatus in the original campaign timetable of 3 months, and only then turning south to create a line of control from Arkangelsk to Astrakhan. Moscow was the nerve center of Soviet telephony, railroads, roads (such as they were) and other means of communication and control. A rump Soviet state might have survived beyond the Urals after this fall of Moscow, but it would have had little power without the manpower of the Russian heartland.
Bingo. Had Hitler allowed his Generals to run Barbarossa, the whole thing WAS winnable - albeit at a cost far, far greater than the Germans had initially thought (having underestimated the number of Russian divisions by - what - half???)
Of course, the thing that (besides Hitler's micromanagement) guaranteed the failure of Barbarossa was the (mostly) Serbian coup-de-tat in Yugoslavia in March 1941, which repudiated the recently signed pact with Hitler, and drove him to delay Barbarossa by a crucial month while he exacted "Operation Retribution" - the conquest of Yugoslavia.
That month made the difference between the Panzers rolling into Moscow in October/November - instead of freezing to a standstill at the outskirts of Moscow in late December 1941.