Yes, if he had planned to do solely and 'overrun' from the very start rather than figuring out that he couldnt kill them later on, he might have had the mass to do so. But to me, the point is that it is AWFULLY silly to have to resort to such a strategy in the first place.
I believe that this strategy is actually closer to the one employed by the Allies than launching attrition attacks. The Germans were very good at blowing up the Allied tanks, but there were just too many of them, and so they were forced to retreat.
I do agree that the German player sitting on a ton of supply in the end game is highly unrealistic. There should be a way to target supply units via air strikes and/or supply units should take casualties proportional to the damage done vs ground units.
Supply shortages were one of the main reasons for the final collapse and a factor in the German inability to maintain offensive operations, something that doesn't seem to occur in the end game here.
A smart German player seeing the noose tighten will spend the last few turns building up an inexhaustible supply depot.
