Despite the cynical nature of that assertion, the basic argument holds true. The Chinese had several thousand years of practice at assimilating (as in Borg-assimilation) of foreign culture, and they did it by standardizing on language and culture.
Even today, if you go China or Taiwan and you start asking about how to say things in Chinese, people start treating you as a candidate for a civilized person, rather than a foreign barbarian.
Having said that, the cynicism obscures a deeper truth. The core teachings of all religions are essentially the same, and for the people who got deep enough to do that, they know that language and culture are "local flavor". They are genuinely trying to help people get in touch with themselves, regardless of age, race, sex, culture, religious affiliations, political philosophy, caste, likes and dislikes, and the wrongs you have done or have been done to you in the past. None of those things are who you are.