I don't think one could replace "economics" and make the claim that it did not play more than a trivial role in cross-national differences in levels or growth rates of GDP per capita or improvement in human well being. I think there is a pretty good case to be made that poverty fell in Vietnam because the overall economy grew very fast and that the overall economy grew very fast because the government adopted good versus bad policies and that the government did this because they were convinced by economics. Similarly for massive poverty reductions in China and in Indonesia. These arguments might be wrong but they can at least be plausibly made with facts. There is nothing similar for RCTs.