I think that Blitzkrieg is also about encirclement.
I think that blitzkrieg is also about conquering cities.
But the principal character of blitzkrieg is to break the enemy will to combat. Morale factors are the main key of blitzkrieg doctrine.
Encirclement of russian soldier could have shaken russian morale, a more important achievement than the simple number of enemy soldiers out of combat. From a practical point of view the human resources of Red Army have overcame the problem in an easy way.
I think that had Moscow fallen, Russian morale had received a more serious hit.
It is for this reason that I have said that having German the Blitzkrieg as strategic doctrine they had to attempt the conquest Moscow.
Had this achievement caused Russian defeat?
All of us say no, because we see the future of the conflict: four year later Russian troops entering in Berlin. And probably the war had continued also after the fall of Moscow.
But that was the German objective, a morale objective to be achieved with Blitzkrieg strategy.
Men fight if they feel that there is a hope for victory. If the morale of the men is broken they more probably will run away more than try to fight a battle without hope.