There are now a multitude of echo chambers, you could easily argue that each user has his own personalized bubble. What is different from before social and personalized media is that there is (much) less common experience anymore, no dominant common denominator like a major newspaper. What Zuckerberg should point out is that – in a way – this is detrimental to what his alleged aim with FB is: to connect people. I'm not sure where this will lead us to. Since I started using FB more intensively I actually feel more disconnected from people than ever.