>>5
Except wars occur between political entities, not corporations (yet). Corporations don't want to kill people, they want to exploit them.
>>6
Protectionism might help on a very local level, but on a larger scale, trade offers more options. If your industries can't compete with another, why insist on creating an artificial barrier to make yours able to compete, when you can shuffle resources in that industry elsewhere to something else you're good at?