> Would people in Indonesia and India join Facebook if it were mostly old people and people from their own countries

Shockingly, people join networks that are used by people they know and their circle of friends is in their own country, for most part. If you think young Indian people are desperately trying to copy what's cool in America you'd have to explain why Whatsapp has been (and continues to be) the dominant network in India, despite being a minor player in America.