I disagree. As long as the idea that an obviously inaccurate description of a person's skin colour is their identity is treated as being valid, let alone actively encouraged and politically dominant, there's little or no chance of people being seen as people. We need to be saying "This view is wrong. It's factually wrong. It's ethically wrong. It's so wrong that it's downright deluded and possibly insane. It is not a valid view." So yes, "the existence of 'black' and 'white' people" should be ignored because it's not reality and it's a dangerous idea. Group identity politics is nothing more or less than the idea that "they're all the same", i.e. the foundation of irrational prejudice. We shouldn't ignore the fact that some people think that way, but we also shouldn't think that way ourselves.