The exact reasons I have never been a huge fan of most forms of social media. I pretty much only use my facebook account because I have some friends and family members that are much more likely to communicate with me on that then any other means.
And here's something I've noticed--there's even an incentive to constantly be on it, because if you're not, like me, you're much less likely to show up in people's feed.

*photo copying your ass crack is a highly underrated practice ;)