In the US (at least) we can no longer have policy discussions, because we no longer share a common reality.

We can no longer empathize, I don't think it's about people living in some alternate reality. Take the example of second amendment rights vs. gun control. What one needs in the city, versus the middle of Montana are going to be very different. If an urban professional can't imagine themselves in Montana, and a Montana rancher can't imagine themselves in Chicago then you've got problems.

I agree that there are problems with empathy, but when people disagree on basic questions of physical science and recorded history, alternate realities are indeed in conflict.

I'm no climate change denier, but should anyone who seeks to question the research be labeled as living in an alternative reality (now politicians who spread reearch that have been shown to suffer from measurement errors and what not is whole different thing)? That's not exactly how the scientific method work.