I'm on various social media sites including LinkedIn and Facebook for professional reasons but I don't mess with them. I weaned myself away from spending time on these sites. My profile is just there if someone wants to see it for professional reasons but I don't interact with people on the sites. So to have it up for professional reasons doesn't mean one needs to engage. A few people from the past came forward but I discouraged a lot of interaction (or even requests to meet in real life) because I simply wasn't interested. I have enough on my plate just dealing with the here and now. I am not a very nostalgic person so what happened 30 or so years ago with school chums doesn't interest me.