Just another item that the Germans can use in their arsenal to keep a factory from being moved. Sacrifice a pz/moto unit to cut the rail and prey on the Soviet unable to fix the darn rail until Dec. It is a hit below the belt but that is in the game and I have done it before myself. Really think the Soviets should be able to fix some rail before Dec.
I understand your point, and I agree to some degree. I find that the game often ends up being partly about "exploiting" game mechanics to the fullest.
However, from a production point of view, I find that the good Soviet player, such as yourself, has an understanding of what needs to be railed out and what can be left behind. That means that he/she will make sure the Soviets keep the required number of Armamanets/Heavy Industry that is needed to supply the Red Army. Named Industry will also be railed out well in advance of the Germans arriving.
That makes long range surprise attacks about the only way the Germns can hit the Soviet production system effectively. Cutting rail is an essential part of this tactic. Still, this strategy requires the Soviets to be caught off guard (as I believe you were in this instance). It would have taken no more than a screen of four or five shell divisions spread out in front of Voronezh to make this attack an impossibility alltogether. I we started the game over, I do not believe you would never make this attack and option for me again.
When playing as a noob against Pelton, I ended up producing armaments for the reserve pool by the winter and spring of 1942 - and that was after losing both Moscow and Leningrad. It required no more than 290 Armament factories and less than 200 Heavy Industry.
In short, I do not believe the Germans can win the game by disrupting the Soviet industry - IF the Soviet player is capable.
PS. In theory, the Soviets can repair rail before December. It requires that no Germans are within five hexes.
PPS. At Stalino, I believe my units are adjacent to the city (meaning double costs for evacuating) but not adjacent to every rail hex leading out of the city (meaning evacuation is possible).
We need only to kick in the door, and the whole rotten structure will come crashing down.
Adolf Hitler, on the eve of Barbarossa.