GoT is a recurring topic on that blog, and in another series [1] - that one on why Dothraki are not an accurate representation of any real-world nomadic culture (despite GRRM's explicit claims that it is a fusion of such) - the author made a reference to that claim:

«The answer to the first is something that we’ve rehearsed a number of times, but bears restating: for most of its readers (and the watchers of A Game of Thrones), A Song of Ice and Fire will be their primary exposure to the idea of the Middle Ages. This is particularly true because of the reputation that the series has for being ‘how it really was,’ a reputation that George R.R. Martin has consciously cultivated (as with his classic complaint of ‘what was Aragorn’s tax policy’ – there is a rich irony that, had Martin understood rulership in the Middle Ages better, he would have understood why Aragorn’s tax policy was less important). Martin has been quite open that he “draw[s] inspiration from history” and that fact has long been a selling point of the series over more obviously fantastical kinds of medieval-themed high fantasy as well as a response to some of the series’ more controversial moments.»

[1] https://acoup.blog/2020/12/04/collections-that-dothraki-hord...