Part of the issue of "echo chambers" is that they tend to be big fans of playing the fallacy of composition -- that is, they tend to take the "loudest extremists" on the other side, and over-promote them to marginalize the entire lot. Sure, radical progressives exist with narrow, dogmatic viewpoints... but these folks do not represent the entire spectrum of liberals / Democrats. The same goes for similarly narrow, dogmatic radical alt-righters or fundamentalists... these are not representative of all conservatives / Republicans. However, within echo chamber media, it is very common to see lots of unflattering reports on "radicals" of the "other side". These type of articles are actually pretty good warnings of what you are going to get.
As far as /r/politics/ and others of similar ilk goes, it seems to me that as a general rule, social media seems to be pretty good at carving out these "echo chambers" way more explicitly. It's probably because the promotional tools are crude (binary systems of likes / thumbs up / thumbs down / etc.)... and outrage-inducing headlines is much better at selling clicks. I personally don't think The Guardian is the greatest example of sober reporting in the world, but at this point I'd take them far and beyond any Reddit political sub I've seen so far, or in fact any mass political board on the Internet anywhere.
As far as /r/politics/ and others of similar ilk goes, it seems to me that as a general rule, social media seems to be pretty good at carving out these "echo chambers" way more explicitly. It's probably because the promotional tools are crude (binary systems of likes / thumbs up / thumbs down / etc.)... and outrage-inducing headlines is much better at selling clicks. I personally don't think The Guardian is the greatest example of sober reporting in the world, but at this point I'd take them far and beyond any Reddit political sub I've seen so far, or in fact any mass political board on the Internet anywhere.