> Also, showing people only what they want to see leads to echo chambers

Not sure I agree with this. The internet made it possbile for the whole world to see information coming from all kinds of sources. Before, in history, you had to rely on local news/newspapers, or even less information. Much more bubbly than this modern age.

Again: I think the reason those bubbles appear have to do with society and the urge to belong to a group, Facebook is not to blame here. Facebook reflects people and society, not the other way around.