I've learned from a more informed friend that technically only Arabia and India are 'subcontinents' and Europe is not a separate landmass in any sense whatsoever. Ivy has brought out into the open (apart from myself) what I'm, yes, complaining about. The arbitrariness of modern-day naming systems, which in turn breed completely erroneous generalizations about "Asian" culture.
The cultural separation idea doesn't fly with me, because from the time of Persian empire and the 'barbarian' invasions from the upper-east of Asia, Europe has been extensively involved with the rest of Asia, including its own excursions out.
Oh well.... I guess I'll write a book and be an angry old man in the corner.