Which doctrine do you refer to?
The Germans do not need to make a complete circumvallatio as the Romans did in ancient times to have an impact. Times has changed.
Siege warfare is a doctrine- it's the belief that surrounding your enemy & cutting them off from all support (starving them out) is better than attacking a heavily fortified position.
Piecemeal attempts at surrounding Moscow would have been disastrous- the city would have attacked from within & without. They might have had an impact but it would have been like kicking Andre the giant in the nuts. You can't kill him- but after he gets off the floor you better run.