> No, they’re coupled issues — eg, open markets forces domestic labor to compete unfairly.

You're still describing economic policies though, not diplomatic ones, and while they're not entirely disconnected, trying to fix international economic issues by burning down alliances is likely to result in a lot of negative second order effects while not even addressing the main economic concerns.

If we're ascribing bad faith motivations to particular viewpoints here though, I'll point out that conflating concerns about trade policies with the idea that America should entirely abandon any interest in the rest of the world is enormously helpful to countries that would like to pursue far more aggressive imperial ambitions currently being blocked by American power. Having rightfully angry people in America's rust belt become convinced that the only way to revitalize the industries that used to power their cities is to let Russia reform the Soviet Union has got to feel like the political victory of the century to Moscow.