LinkedIn really blew it. They were the one of the big social players (Facebook, Twitter, G+, Foursquare, Tumblr, LinkedIn) that had people who were happy to pay for premium features. Put another way, they were the only social player with a non-ad revenue play. The problem was that the people paying were recruiters, so they did a lot to make the recruiters happy. They forgot about those who the recruiters were targeting, however, and now people like us send LinkedIn straight to spam.

LinkedIn had a real opportunity to be the social network that added real value, but now (as evidenced by the comments below) people see them as a spammy, shady mess.