The assumption being made of course cultures must only change from external forces and that they cannot change internally. It comes from an ancient caste based world view where people are defined by their birthright and do not change from this, that we know now is foolish to believe in.
Yep. Trying to steer culture is like grasping at smoke
Smart phones and social media have impacted culture most places far more than a few immigrants ever could - folks should spend more time worrying about those and less scapegoating of immigrants