Disagreement is completely different from what I was talking about. People on the left are aware of the fact that those individuals claimed self defense; most disagree that it should have counted as self-defense. The fact that you saw their opinions in the first place -- and they saw yours -- shows that. If you think their opinion is wrong, or if they are too unwelcoming to your opinion, that's a separate issue. I'm not even talking about the merits of either argument here, I'm talking about the fact that people on the left at least tend to know what point they are disagreeing with. Non-conservative news outlets will at least report "George Zimmerman Claims Self-Defense," or "Popular Progressive Politician Receives Criticism from Own Party." Right-leaning news outlets outright shelter their audiences from such information.

In my experience of trying to reach out to conservatives, as our culture of respectful disagreement expects me to, I am constantly blown away by the fact that a typical conservative has no idea what the objection to their worldview even is. Trump got elected almost eight years ago at this point, and they will still drop something like, "So what exactly do you people not like about him?"

There are levels to echo chambers. America's Republican voters are sheltered in an iron dome, where dissenting ideas don't even get in at all.