> The border crisis is a good example of this.
In my experience, the biggest contributor to the echo chambers is a lack of memory.
I do not think people's memories are bad, but rather they willfully ignore the other party's position, never learned it in the first place, or are justifying it because their party is in power. This is what centrists frequently get mocked at "both sides" about. They aren't saying "oh both sides are trying to stage an insurrection" they are saying "both sides are not going to let immigrants across the border" (but it'll be generalized to everything being both sided).
I think the way to cure this is also the way to make parties better. Criticism. We should always critique our parties to make them better. Unless you believe they are perfect already and getting direct commands from god, it is deserving of criticism. But we've encouraged a culture where criticism isn't (effectively) allowed. It is allowed by certain people who speak in a certain way, but not for the average person. (e.g. if you are speaking to someone you don't know that well and politics are brought up and you criticize something x party recently did it will be presumed you are of the opposing side). I believe part of this is because we are comparing politicians and parties rather than judging them independently (this is also why I'm a big supporter of Cardinal voting as opposed to the common Ordinal propositions).
This is essentially the root of whataboutism. The classic example is one I had my parents many times over the last decade. I suggest Trump should be investigated for his connections to Epstein given his frequent contact. And my dad would be like "but what about Clinton!" and my response has always been "yeah, him too." Because it isn't about parties, it is about the crime that was potentially committed. If something is bad, then it is bad if the other party does it or if your party does it. Tribes don't matter. The whataboutism is just a distraction technique.
TLDR: Don't forget the past. Criticize everyone. Stop saying "what about...".