Among my Facebook "friends," I don't participate on the platform very much. Certainly nowhere near as much as some people I know. People who seem to be spending most of their waking hours "sharing" everything they can think of on Facebook! The utility of Facebook is a fact of life today. It wasn't always like that, I joined when Facebook had only around 10 million members. Now they're at 1.5 billion! That's a utility.
Unlike other utilities (such as PG&E or AT&T, for example), Facebook is interactive and invasive - it's roots buried deep into the psyches of its customers. The more Facebook grows, it's user base becomes just that much more varied and multinational, giving the "powers at be" tremendous data to be mined and marketed to.