Has politics ever not been post-truth? To win a debate you just need to sway the audience. It has been known since ancient times that's not limited to presenting facts.
Now you can close yourself in a bubble without ever having to confront any view you do not like.
I think it's kinda like how technology hasn't changed the reasons behind wars, or their intrinsic nature, but has definitely changed their impact and their scale.
You can now lie yourself into and out of basically anything, without ever having to face the reality of what you are saying or suffering basically any consequence. I think that in one way or another, our society and political structures will have to evolve in order to take this into account.
“People like you are still living in what we call the reality-based community. You believe that solutions emerge from your judicious study of discernible reality. That’s not the way the world really works anymore. We’re an empire now, and when we act, we create our own reality. And while you are studying that reality—judiciously, as you will—we’ll act again, creating other new realities, which you can study too, and that’s how things will sort out. We’re history’s actors, and you, all of you, will be left to just study what we do.” [1][2]
1: https://en.wikipedia.org/wiki/Reality-based_community
2: https://www.nytimes.com/2004/10/17/magazine/faith-certainty-...