why does it explain a lot? It just seems like people are assigning themselves a high moral ground here that is completely undeserved, just because they identify with a specific political group. Anything that disagrees with this political group's ideology is immediately labeled "regressive" (whatever that even means) no matter what the points of disagreement may be. Case in point - if you question the 12 year death sentence certain politicians have put on the planet due to the man-made climate change hypothesis, you are suddenly "regressive", which is just plain silly. Being "progressive" seems to be to actually be pretty regressive in a lot of ways, and extremely damaging to the environment and the economy.
So to sum up, the moral preening of those labeling themselves "progressive" is pretty hard to stomach, and also pretty hypocritical.