The country as constituted can no longer respond to crises

This has always been the case, since at it's founding the US has been a dictatorship of the bourgeoisie. The very mechanisms that stamp out popular pressure at the expense of the capitalists also prevent it from responding to crises. It's no accident that all our legislative rules and structures make even passing a simple bill to raise the minimum wage damn near impossible. That's why I have zero hope of stopping climate change outside of a proletarian revolution.