By Marc A. Thiessen The left complains that conservatives are “obsessing” over Alexandria Ocasio-Cortez. Well, there is a reason for that: Ocasio-Cortez is driving the agenda of today’s Democratic Party — and her economic illiteracy is dangerous. Case in point: Last week, Ocasio-Cortez celebrated the tanking of a dealnegotiated by her fellow Democrats in which Amazon promised to build a new headquarters in Long Island City, New York, right next to her congressional district. Amazon’s departure cost the city between 25,000 and 40,000 new jobs. Forget the tech workers whom Amazon would have employed. Gone…