monty, you are right there; Decentralization worked, even though the area bomb period, it had the "hardening" effect described, and - while it destroyed infrastructure for the civilians to an unknown before extent - did not really harm production numbers.
Production was much more influenced by denial of critical materials.
Rattler
Do you really believe that who is more productive 20 small factories or one big one, the modern model plumps for the big one. So did the Russians who amazingly managed to move most of their manufacturing bases when they were about to be overrun. Add to this logistics of supplying lots of little ones & what meagre resources dont get through due to disrupted rail lines. Did it help slow things down & take pressureoff the Rusians unquestionably yes. Material shortages & getting them to a scattered workforce had a huge effect. APCR virtually none existent & brittle armour being just 2 the numbers might have held but many late production tanks were prone to shatter, then theres spare parts.