Google serves the search needs of the masses, whereas social networks appeal to what people want. It’s utility versus leisure, simple as that, or what a blog post refers to as catering to pandas and lobsters. At the risk of oversimplification, it’s akin to the left/right brain divide, the IQ versus EQ hemisphere, or the introvert/extrovert behavior. Search and advertising is the core competency of Google, putting its fingers to where the market pulse is. Search is what Google is all about, other endeavors are just extras its coffers can buy.
Search is Google’s identity. Google is about getting the job done. On the other hand, social networks do nothing but panders to the lobsters. It’s about wants and needs. People can live without social networks but not without Google. Google is a necessity just like water and oxygen.
Google serves needs what social networks serve as leisure. Period.