Question: Why can social media often be described as an echo chamber?
I think that your answer is,
When people are on their cell devices and using the internet, they tend to block out things around them such as, someone telling them that on Tuesday someone will be calling them or, they have an important event coming up, and the person being told that is or was on their cell device at the time forgets what they were told. An echo chamber is when someone isn't paying attention to the real world and is caught up in social media.