What happened to social media being a conversation platform instead of an echo chamber?

We are what we read online and this can be dangerous. Curated and personalised news feeds are driving us into holes we might not be able to dig ourselves out of – meaning, we’re becoming more and more self-absorbed with those that share our own views. It’s like an episode of Black Mirror, but instead it’s reality.
Maybe it started with Facebook's 2013 addition, the 'unfollow'. It gave users the ability to quietly unsubscribe from a friend’s feed without their f