Kurds are as "native" to Erbil and the Nineveh plains as much as Ashkenazis are to Israel. They settled that land after massacring Assyrians with their Ottoman overlords less than a hundred years ago. At the same time, they operate like a political mafia in Kirkuk where the KDP has been documented to threaten and kill Arabs and especially Turkmens out of their homes, not to mention its total seizure a few months ago. HRW has also documented seizure of property for the many displaced during daesh. Even though that whole episode was taken advantage of through and through, they remain a small majority (~50%) of Kirkuk at best.

There would not be anything to stop the referendum from granting full independence if they hadn't illegally occupied Kirkuk but of course, that would result in a resourceless, landlocked country without any unfairly generous federal funding for the Barzanis to embezzle. The average Kurdish nationalist is too blinded by tribalist dogma to ever realize they are the greatest obstacle to themselves and others.