Simple models shouldn't be applied without nuance (and that's why I get really annoyed at "engineers" on HN who think they know jack shit about economics becaus

Simple models shouldn't be applied without nuance (and that's why I get really annoyed at "engineers" on HN who think they know jack shit about economics because they took econ 101). The idea is sound, but the real world is more complicated. In a simple world model where there are two industries of equal value and two countries with complementary specialization in these industries, it makes sense. There is an opportunity cost to closing the borders and trying to do everything yourself, which you are not considering.