Interesting perspective, Tony.
I rely on LinkedIn for my professional network (and only professional). It's useful to me for that purpose because I won't allow my professional network into my Facebook space. My rule with LinkedIn is that if I don't know you and haven't worked with you in a professional setting, we're not going to be connecting there. My Facebook (ugh! can't get away from it) is strictly for friends and family (work friends don't count, they're on my LinkedIn account).
This is why I love G+; with the circles I can easily separate work, personal and other into tidy little spaces, all in one place. Wish everyone was here.
Just as an FYI to duplicate account problem: I did see this on LinkedIn (you piqued my curiosity about the problem): http://help.linkedin.com/app/answers/detail/a_id/1275