When you put many similar filter bubbles together, you get echo chambers, where the same ideas seem to bounce around the same groups of people, echoing around the collective chambers of these connected filter bubbles. Echo chambers result in increased partisanship, as people have less and less exposure to alternative viewpoints. And because of availability bias, they consistently overestimate the percentage of people who hold the same opinions.
Chapter:
Being Wrong Less
Section:
In The Eye of the Beholder