Look at the latest edition of QJE. You will see mostly studies addressing a particular policy question, e.g., 'what was the effect of this policy change on unemployment' which they answer using randomly controlled trials or quasi-experimental methods. Which aspect of this falls apart when you prod it?

I was more thinking of top economists like Alan Greenspan and his comments about having banished volatility, followed shortly after by the '08 crash.

Much of economics is politics disguised as technocracy.

Of course it is. Economics uses to be called political economy for a reason. The idea that economics can be considered separately from politics is laughable.

What's a "quasi-experimental method" and how do you do randomly controlled trials on entire countries?

Quasi-experimental variation refers to situations in which assignment of treatments is 'as good as random' but treatments weren't assigned by the researchers in an RCT. A classic example is Angrist and Lavy https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...