Which went through a bloody religious partition in 1947 to become two separate countries because of incompatible competing cultures not able to live together. And one country promptly wiped out the other culture almost completely to become a mono-culture. And that enmity between the two countries (cultures) follow to even now with wars and other hostilities.
What is called multiculturalism in India is a mix of indigenous sub-cultures who share many similarities, which the different cultures of EU/Europe can be considered to be following as well.
> two separate countries because of incompatible competing cultures not able to live together.
India has one of the world's largest muslim population. Pakistan separated due to religion and not culture. In fact Pakistani has Punjabis that are quite similar to Indian Punjab and Bangladesh & Indian West Bengal has quite similar cultures.
> What is called multiculturalism in India is a mix of indigenous sub-cultures who share many similarities
Are you claiming that Assam, Gujarat, Tamil Nadu and Bengal cultures are the same? They dont even share the same scripts (and in case of Tamil it is even a different root language)! They may be sharing same religion for majority of people, but that does not make it a subculture.
Existence of a minority currently doesn't negate the strife it passed through when those minority numbers were much bigger. Which still exist in regions where the numbers swing the other way - kashmir.
"Indigenous sub-cultures who share many similarities" doesn't mean "cultures are the same". All their current scripts originating from the same Brahmi script is part of that shared culture.
Your example of multiculturalism is more in line to the indigenous cultures throughout EU/Europe sharing similarities. While the context of European discussion on multiculturalism is on migrants and their culture.
Ethnicity and culture is mutable and always will be. People move and intermingle. That is human. Trying to artificially isolate a group of people with a particular set of genes is unnatural, gross, and eventually leads to genetic stagnation. Your thinking is backwards and unsustainable which is why movements espousing these views always fail.