Somewhat off-topic, but why are we lionizing Reid Hoffman? It's well-documented that LinkedIn uses extremely shady growth hacking tactics. One of my friends granted LinkedIn access to her Gmail contact list, and LinkedIn proceeded to spam every single contact with an invitation to connect.
[0] http://marknugent.tumblr.com/post/98203319356/linkedins-evil... [1] https://gigaom.com/2013/09/21/linkedin-is-breaking-into-user...