I’m smart enough to know what I don’t know. So I’ll let a friend of mine, a university Director of Global Outreach and Engagement, whose research focus is language maintenance in immigrant communities and multilingualism, give you three examples for you to further research.
“China has 56 officially recognized minority groups. If it weren’t for China Japan wouldn’t have writing so I’m going to say yes, they’ve benefitted from multiculturalism. Same with Korea.”