Before that, the term "economy" was only used as a synonym for thrift or a system of management or control (and "economist" tended to mean someone who wanted to reduce spending or increase restrictions on something).
Reactionary liberalism, e.g. neoliberalism, Austrian school, that kind of thing, discards the 'mess' of interdisciplinary approaches and seek a return of a protestant worldview, riffing off of their use of the New Testament verses about "render unto Caesar". This puts them in harsh ideological conflict with the political economists and elevates their 'theology' above the work of previous scientists.
Historically some trace political economy to ibn Khaldun, but in the Occident it's Ricardo, Mill, Marx and so on that create a (to us) recognisable science out of it.
You could easily fix that with a bit of effort.
> He didn't follow the scientific method.
Science is not the only legitimate form of gaining knowledge. What you write applies to every philosopher. And economics is not generally known for being the most scientific of all sciences. This is all the more true of neoclassical economists, who are probably closer to your worldview if Marx triggers such a knee-jerk reaction in you. Whether you like it or not, Marx was a gifted systematic and analytical thinker. Even his ideological opponents admit this. At least if they can hold a candle to him intellectually...
Central America, the Balkans, the Levant. The Iroquois and Algonquians. Cuba. The Medicis and the Stuarts. And, as you say, revolutionary Virginia and Maryland. Lots of potential there for a grand narrative covering 600 years or more!
(And, to gp: yes, it absolutely did threaten governments, empires, and entire political systems!)