> Externalities are the activists’ favorite technical-sounding economic concept because they introduce a fudge factor into every single economic process that can be abused to support almost any conclusion.
Citation needed.
Yes, they're a favorite. But I always thought that it was because economic models are usually simple, closed systems and that's a trivial, approachable way to show that they're wrong.
Similar to finding "bugs" with provably correct functional code. Wherever it touches the real world, it's no longer simple math and something hinky's bound to happen.