A point about the echo-chamber, though:

Sometimes, if you are optimizing for humor or whatever, an echo-chamber is exactly what you want, because the social mores and cultural touchstones are the same. It's also very hard to have people with widely diverse viewpoints in these groups (worth it though!), because the tendency is just to turtle up and argue back and forth and back and forth and generally suck the air out of the place for anything else. This makes it not fun, and that drives people away, and then your channel dies.

If you want to try that, you need people that are willing to find a point and say "Okay, we clearly agree to disagree here, and let's move on and not revisit this unless circumstances really change or we are just being academic". That's a sort of civility, though, that is very rare.

It's also difficult because you have two people who are meeting and usually who have very different echo-chambers they subscribe to, and so even when they do enter into a discussion they are doing so from such divergent starting points that they're more likely to talk past each other.

There is no environment that would lead the author of parent comment to "empathize with alternative points of view". That's why backchannels are valuable.