It is interesting though to contrast and compare the implications of David's diagram with the study looking at how information is shared on Facebook, published on the Facebook Data Page: Rethinking Information Diversity in Networks. The report basically states that:
….even though people are more likely to consume and share information that comes from close contacts that they interact with frequently (like discussing a photo from last night’s party), the vast majority of information comes from contacts that they interact with infrequently. These distant contacts are also more likely to share novel information, demonstrating that social networks can act as a powerful medium for sharing new ideas, highlighting new products and discussing current events.
David's diagram is about the whole matrix of online relationships, while the report relates to Facebook only, but do they concur with each other? I'm not so sure.