Contract systems emerged well before WWII, before industrialized society, even. When some knight needed a new spear he hired a local blacksmith. Centrally operated foundries specifically producing arms were quite rare, usually a feature only in large empires with professional militaries.
Rationing necessarily implies that there is a market economy to regulate: the whole reason why the government had to limit the production of civilian vehicles is because the wartime economy was still a market economy. Ford, GMC, etc. were still private companies at the end of the day, participating in a market economy. Rationing made it more attractive to cater to military acquisitions.
Different companies working competitively has consistently proven to put outcompete and surpass centrally planned economies. Lockheed Martin and Raytheon continue to export way more arms than most other companies, competition may mean information gets siloed but evidently it gets results.
Rationing necessarily implies that there is a market economy to regulate: the whole reason why the government had to limit the production of civilian vehicles is because the wartime economy was still a market economy. Ford, GMC, etc. were still private companies at the end of the day, participating in a market economy. Rationing made it more attractive to cater to military acquisitions.
Different companies working competitively has consistently proven to put outcompete and surpass centrally planned economies. Lockheed Martin and Raytheon continue to export way more arms than most other companies, competition may mean information gets siloed but evidently it gets results.