I'm sorry, this is just sententious bloviation. The sources are so thin, there's no reason to go around imputing all these fantastical ideas that somehow benefit your own beliefs. It's just boring and insipid to watch people fall into this trap over and over.
Agreed, the article contained a lot of speculation and not many historical examples. It was more about what the author thought “made sense” than what reality was.
It was also quite long winded. Probably could have been summarized to maybe 3 reasons. Oddly enough I don’t see “money” mentioned, at least not simply, and that should probably be reason #1
This is a blog post (not a paper) written for a general audience by an academic summarizing content he has gone into greater detail on in his other blog posts which generally have more links to further reading - and this one also opens with suggestions of three or four books that provide a deeper overview of the topics it goes into.
It also doesn’t pretend to be anything other than the author’s opinion about how fantasy world builders might better incorporate real world historical analogues into their stories for greater verisimilitude – and, yes, to further Bret Devereux’s explicit agenda which is to counteract what he sees as historical misinformation perpetuated by fantasy authors adopting a sheen of ‘based in realistic history’ while actually doing a disservice to ancient and modern people and their histories.