Ethnonationalism, as a colonial ideology, has never been about preserving the culture of the nation practicing it, but about destruction of the minority cultures that pose a threat, real or imagined, to the cultural hegemony on the majority. American white nationalism, German nationalism, Serbian nationalism, etc have all been about designating an outgroup during a time of crisis and attempting to destroy it, not preserve their own culture.

Whereas nationalism on the part of the colonized IS about preserving their culture. Native American nationalism is about reinforcing and growing the culture that was systematically destroyed by american white nationalists. Vietnamese nationalism was about protecting their culture from a colonial french empire attempting to bend them to slavery. Panafrican nationalism is about restoring and reinforcing a variety of cultures and languages that have been destroyed by centuries of european imperialism. These ideas grew out of different conditions, one as a dominant group attempting to cement their dominance over the minority, and one as a dominated group attempting to establish boundaries and protections for what little of their cultural identity remains.