When did social media stop being social?

Hello all,
So today I had an interesting lecture on the topic of eprofessionalism. We were discussing whether employers should use information found on social media sites about prospective new hires in there hiring decisions. I was against it. I have always lived by the rules of separating my work life from my social life, and I would think it to be unfair if I was to not be hired just because I was at a social event drinking or said a sarcastic statement to a friend that was taken out of context. After class, I came across an interesting article about people being fired for things said on their social media sites. Really, when did social media sites stop being social. So if I took anything away from that lecture it was... Privacy Setting are key! Use them!....Or find another way to keep in touch with old friends. Here's the article if your interested. http://www.lexisnexis.com.ezproxylocal.library.nova.edu/hottopics/lnacademic/?verb=sr&csi=299488&sterms=PUBLICATION(Giving+Business+to+Social+Media)