What you're describing is an echo chamber, when people willingly share only things that they know resonate with the group. While still somewhat detrimental, it

What you're describing is an echo chamber, when people willingly share only things that they know resonate with the group. While still somewhat detrimental, it's at least a visible problem - everyone is aware of it because everyone sees the same thing. With filter bubbles, you create personalized echo chambers, that nobody is aware of unless they're in there.