I find it really, really pathetic that the collective American psyche was/is so fragile that one experience -- yes, a truly terrible experience, but still just a single major event -- has shattered and drained our entire cultural reservoir of goodwill and ethical perseverance. All it took to tear down the facade of American benevolence was one day dealing with what half the planet deals with on a continuing basis. A decade and a half of spinning our wheels and doing more harm than good in the Middle East doesn't help, either. I have my own amateur theories as to how that, maybe subconsciously, plays into this "Make America Great Again" business. But whatever the effect of exposing our fundamental cowardice and petty lust for vengeance, it definitely goes hand in hand with a population retreating to the physical, emotional, and intellectual safety of the familiar.
This is a trend that possibly would have been a factor in public discourse even without the software and systems that are turbocharging it. It might be enough to (at least partly) explain why the Internet -- a system that does put us in almost direct contact with most of the rest of our species -- has pushed us farther apart rather than closer together.
So I think any response to these unconsciously self-imposed ideological echo chambers has to have a few different facets. Yes, we need to draw attention to the fact that by preferring certain information, you are necessarily excluding other, possibly more worthwhile, information. But people -- and I mean Americans because that's all I really know -- need to be reminded that the only reason "The Left" harps on and blames America as all the time is only because we believe America could choose to be all the things our propaganda claims we are. Brave, and free, and strong, and good. Because the way the systems work, even if they are somewhat amended to provide a counterbalance people's limitless ability to pursue bad information, just waking people up to the fact that that's what they're doing won't be enough. They have to be pushed, even inspired, to do something else instead.
Or something.