It's because of the ratio of reads to writes. For many applications, especially in social/content, the creation traffic is an order of magnitude or two less tha

It's because of the ratio of reads to writes. For many applications, especially in social/content, the creation traffic is an order of magnitude or two less than the consumption traffic. So free inbound bandwidth is a bit of a rounding error. Here's a somewhat old article that captures the rule. http://www.guardian.co.uk/technology/2006/jul/20/guardianweeklytechnologysection2?mobile-redirect=false http://www.guardian.co.uk/technology/2006/jul/20/guardianwee...