I joined LinkedIn a few years ago because my uni friends had done it. I've updated it occasionally and used a flattering picture that is semi professional (I haven't dared go for the professional 'author' picture yet.). I haven't relied on it a lot to network as being freelance means I don't tend to make many real life connections, and adding people I've met once isn't my thing even on Facebook. I have 59 friends, and no, I'm not a weird loner or bunny boiler type, social media is a part of my life but it's something I see as a tool to connect with people that mean something to me.
My profile on PPH has yielded a new connection, a guy has got in touch with me about taking on extra work when he can't handle the flow of it. I consider it a great thing that someone's taken the trouble to find me especially when PPH don't disclose your surname. Anyone who's internet savvy can track someone down with a picture and a couple words.
I take it all as a good sign that someone wants my writing skills, I must be doing something right!