See this is what plastic and fuel and steel causes. Everything requires oil right? But what if you dont get oil? In civ its to valuable and rare to trade it correct? And its easy to make sure a civ doesnt get it and then they have no chance to do anything. And if i make it more common it is inacurate and essentially useless.
So now you take fuel, all of a sudden a civ with one oil, and 10 cities, can make 10 fuels. So now everyone has fuel, which is realistic, but the people that actually have the oil get the most benefits since they are teh one making thee fuel, they get the money etc back for it when they trade it. It is a great way for everyone to have it yet keep the advantage to people taht have actual oil. It would be the same for steel and plastic
Also according to wiki your wrong on the steel part, HEAT did put it out of buisness, but only steel alone. According to wikipedia, the top three materials to used in tanks for anti-heat weaponry was plastic, steel and ceramics. They used completely steel plates, but had plasitc and cermaics in between steel plates, which gave it protection against HEAT.
It was invented in the Uk, you should know