If you build a closed ecosystem, you and you alone are responsible for its value. As with other forms of leverage, you win on the upside, but there's also a lot to lose going down. LinkedIn is a closed, walled garden. It's gotten increasingly obnoxious (enough so that I've pared my legitimate profile down to its bare bones, and have a spoof one I use for research). And, well, we've seen any number of walled gardens implode spectacularly.

Logged into MySpace recently?

Could linkedin use it's data for nefarious purposes? Yes.

Could some professionals ask to be compensated for being on the network? Yes.

Have the professionals on linkedin realized the above? No.