He's got something of a point, in that there's a definite cultural difference between the sort of games people from different countries make.
In the case of music (which is my field of study)
almost all folk music is basically the same, Bela Bartok's ethnomusicological studies confirmed this (I'm also in the process of publishing a paper on him, so I'd know :p). Most of the cultural difference comes from the different rationalizations of worldviews because of language. The way we think through specific languages informs our worldview, so this isn't something new. That doesn't mean you can't use other people's cultures to make your own creations regardless of what nationality/culture you are. Bartok used sources from many different folk musics (not only Hungarian) to construct something modern (i.e. lacking tonal relationships, lack of leading tones, different scales etc.), so *how* exactly you use the folklore elements is the important thing, not that you have them. I don't think the Witcher 3 does something interesting with its "Polishness" (if such a thing even exists, that's also somewhat complicated), it just copies some elements from it. In the case of Bloodborne there isn't anything that screams "Japanese" even from a folklore perspective. It has a Victorian aesthetic with the weird fiction of mostly American writers (Lovecraft, Poe). This just cements the point that culture isn't a monopoly.
Outside of folklore there really isn't much on a cultural (national) basis, art is what makes a culture, not your country's marketplace relationships. We might have specific cases (the USA) where these relationships ARE the culture, but that's pop culture and not a truly meaningful one. Besides, filtering your art through consumerism is what we see in the big publishers in all media. We know it doesn't go anywhere.