You’re not a “doomer”, as I read it more like the opposite- your defense of global trade is optimistic. Trade and specialization doesn’t work nearly that cleanly in practice.

Companies and governments saw the disruptions of the past few years and realized that there are unaccounted for costs (and benefits) to the global supply chain. COVID, shipping disruptions (strikes, Evergreen, prices), the chip shortage, etc. all have taught a lesson about the diversification of supply chain risk. Decentralization isn’t less efficient when you include those costs. So it makes more sense now to make goods in America for America, and make goods in China for China. Not all goods, obviously, but the scales have shifted…and that’s a good thing for the health of global supply.

what you say is ideally true, but it ignores the complexity of the system: free trade works great if everyone acts in the best interests of the whole, but game theory tells us that even a few bad actors have the potential to ruin the whole thing (this plays out time and time again with monopolies, negative externalities, etc)

plenty of countries around the world don’t play fair, and that leaves everyone else worse off… you can’t assume the game is fair when it’s actually rigged

we can still encourage trade, fairness, interconnectedness, and efficiency whilst not falling prey to being taken advantage of

we can’t let perfect be the enemy of good here: there’s a balance to be struck, until all of the worlds economies play by the same rules

Yep. This is exactly what they teach in Econ classes along with the idea that by being economically entangled no country will want to behave badly because it will ultimately hurt them (so it will help keep peace and avoid wars).

Unfortunately they gloss over some key parts of reality. First is that this is all “long term” change. Until that point, however, there are going to be lots producers that will have huge losses in the interim as their businesses are offshored. Some people might win, but that’s not much of a consolation to everyone who’s now jobless.
Second is it’s important from a national security perspective to be self sufficient - or at least have to capability to be self sufficient without major disruptions. Unlike the examples in Econ classes, we’re not just talking about apples and bananas. We’re talking about things like semiconductors, rare earth metals, etc. If we have to get into a conflict with another country, we’ll be screwed if we’re dependent on that other country for key inputs.
Which brings us to #3 - economic entanglement hasn’t prevented countries from behaving badly. It’s actually done the opposite by enabling bad actors to behave badly. Look at China & Russia. China has been committing genocide against the Uighurs and we should have cut them off until they stopped, but we can’t because we’re dependent on them for so many products. It’s a similar situation with Taiwan - we tiptoe around the issue of them taking over the island because we need them financially. And the EU was hesitant to go up against Russia because of their dependence on their natural gas exports.
While ideally a rising tide lifts all boats, we’re seeing that it’s not exactly playing out that way - partly because the “assumptions” Econ professors talk about miss key points of human nature. The primary one is that people will act in a way to maximize wealth. But that’s not true. Power and social status can be much bigger motivators than cash - especially when you already have enough cash to live an extravagant lifestyle (like Pooh and Putin).

It may make the economy less efficient on paper, but that doesn’t take in to account the external costs of trade. In return for cheap products, we gave up a strong manufacturing career base and replaced it with low quality service industry jobs which pay less overall. It’s one of the factors that’s led to wage stagnation, which is WAY more damaging than more costly products.

That’s not even to mention the environmental costs of shipping. The literal tons of heavy fuel oil that are burned to get the bananas from Farmer Fred are now causing sea level rise and changing weather patterns, which makes both Bob and Fred lose in the end.