Re: LinkedIn is spam anyway.
You are missing the point that it's a work based site - it's not Facebook. It's for keeping track of work based connections who you might be able to use to benefit your career in the future. Not because you like them.
It's also useful as a barrier between recruiters and your actual email address / phone number because you don't HAVE to share your details with them when they spam you.
Also, if you have a decent profile you can actually get head hunted by good employers from there (not recruiters). It happened to a friend of mine - lucky bugger.