I think the privilege that they were referring to is how most of us here are likely from a developed country with a strong economy and high quality of life, and

I think the privilege that they were referring to is how most of us here are likely from a developed country with a strong economy and high quality of life, and therefore have little fear of loosing our cultural heritage. We are quick to dismiss cultural diversity as trivial and meaningless because countries like the US are such a broad cultural mix, but often most of the population never has to experience either their culture being taken away from them, them being forced to move, or them being colonized. Because of that, people don't understand what it is like to experience colonization or cultural integration. As benten10 said, regional identities are usually convenient wrappers for same culture. People will embrace their place of origin because it is home in the deepest most human sense of the word. However, because we desire to remove the labels of regional similarity (you used nationalism, presumably with the intention of it being a loaded word), doesn't mean that others feel the same way. It is the privilege that we have that we feel comfortable from our place of relative cultural safety that we don't have to be afraid of loosing the things that we feel are valuable to us.