Now that's a very interesting point, Pica Pica! Do you think that the style is common across cultures? It's just because it seems to be independent of the epoch and the region where it was written; all write in the same way.
Of course, I'm aware that cultures were actually much more in touch with each other than we usually like to think, but, still, it's a bit strange.
It would be like finding a lot of different cultures around the globe spontaneously writing in English in the 12th century.
I'm not saying that you're not right; I'm just saying it's a very interesting point you make!