Modern economics doesn't really have a theory of value, which is a 19th century concern. (Arguably, Quesnay was the first person to have a theory of value.) Or, if you prefer, economics have a subjective theory of value. This has some normative content -- if you think the purpose of human existence is the greater glory of God you will find economics pretty disappointing -- but economists no longer try to explain what things are "really" worth.
Your argument is an example of what I mean, though. The labor theory of value lost out on "is" grounds -- there are too many things it can't explain. Now some of the people who made this argument were right-wingers, so if you think that only "ought" questions matter, the fact that people with the wrong notion of "ought" made a contribution proves that the whole thing is morally bankrupt.
There are economic historians, but economists don't talk about medieval or ancient economies just because they don't have much to say. Historians are better equipped to understand them. Though a recent paper applied a trade model (the gravity equation) to predict the locations of Assyrian ruins, so maybe there's more to be done.
Your argument is an example of what I mean, though. The labor theory of value lost out on "is" grounds -- there are too many things it can't explain. Now some of the people who made this argument were right-wingers, so if you think that only "ought" questions matter, the fact that people with the wrong notion of "ought" made a contribution proves that the whole thing is morally bankrupt.
There are economic historians, but economists don't talk about medieval or ancient economies just because they don't have much to say. Historians are better equipped to understand them. Though a recent paper applied a trade model (the gravity equation) to predict the locations of Assyrian ruins, so maybe there's more to be done.