Are you telling me that GoT isn't loosely based around things from the past? That any similarities between the things and events in the show/books and real things and events in history are purely coincidental? You don't think that GoT in particular, or the swords-and-spells fantasy genre in general, aren't a little bit based on mediaeval Europe? When you first watched/read GoT, you didn't often think things like "oh yeah that's just like Hadrian's wall!" It's just a coincidence that all the costumes, characters, titles of nobility, rules of inheritance, traditions, occupations, buildings, and socio-economic circumstances looked a little bit like those might find in mediaeval Europe?
I think it's safe to say that it's based on mediaeval Europe. If the author wants to choose a more accurate rendering of mediaeval life than those traditionally chosen by other fantasy novelists, then surely that's an a priori good thing. I don't think you can criticise it for being more realistic.
Sent from a phone, apols for any mistakes.