Both Google and Facebook offer Advertisers something novel. Google has Search, Maps, YouTube & Gmail data it can use to offer high degrees of targeting through AdSense. Each of these applications alone is nearly the same magnitude as Reddit. Facebook has one of the most complete networks of human relationships the world has ever seen. With their embedded Like Button they can gather data on these users even when they're not on the site. They give advertisers the opportunity to target groups in ways previously impossible.

Reddit seemed to follow the path of traditional media such as newspapers for a long time, thinking static ads were enough. Viral 'organic' marketing seems to be one of the most valuable services the platform offers, and other firms capitalize on this, but it's tricky for them to capitalize on this and maintain their credibility.