Earlier quoted context omitted.
National security is the obvious reason. That includes the ability to switch to a wartime economy, which requires low-tech manufacturing and resource extraction to not be reliant (and thus vulnerable) on imports from potential adversaries. Maintaining a talent pipeline is also important, we’re not going to be able to produce enough high skill machinists quickly enough when we need them because that takes time. Manufa…
The best national security is for it to be in the interest of the counter party to trade with you rather than attack you. Tariffs and protectionism tilt the favor closer to attack. In the extreme, a nation that completely refuses to trade can't offer nor take anything beyond spoils of war.
Sure, but if your biggest export is your country's particular flavor of monopoly money, is it actually in your counterparty's best interests to trade with you?