Because the economics literature is quite clear that international trade is beneficial to all involved. It's what we insist that developing countries focus on exports when loaning them money. For many years, Taiwan has been the poster child that we point to when trying to change the ways of Cuba or Venezuela.
Are these principles so weak that we would allow a dictator who doesn't even have the support of his own people to shake them?
If you narrowly focus on economics, yes. But what are other consequences, outside of economics? By outsourcing everything, you lose control. You allow uncontrollable external factors to affect you. You open yourself to be blackmailed.
So in a way yes, those principles are weak because they are incomplete. They do not take into account the full range of possibilities that can happen in the real world.
Some supply chain instability is the result of allowing healthy economic activity especially when the modern goods we're talking about are immensely complex and require incredible specialization to reasonably manufacture.
Because if they don't, and the system collapses, then what?
In practice the principles don't matter too much. The reality is that industry has optimized for cost and converged on a small set of suppliers. The single points of failure introduced as a side-effect of this could certainly be exploited by a bad actor.
But what kind of trade? Not unrestricted - Taiwan itself used protectionism to grow its industries when they were not yet able to compete on the global market:
James K. Galbraith has stated that [..] " ... none of the world's most successful trading regions, including Japan, Korea, Taiwan, and now mainland China, reached their current status by adopting neoliberal trading rules." - https://en.wikipedia.org/wiki/Comparative_advantage#Criticis...
Maybe the literature is wrong?
lmao