You have the right to remain silent!
I think that before the Internet, LinkedIn, email, etc. most workers were "trapped" by the corporate employment system since they had no way to promote and market themselves. Companies, on the other hand, continually promote available jobs through newspapers.
However, LinkedIn is just a public highway. You still need a "car" to get to where you want to be. In other words, you still need some kind of promotional vehicle to spread the word about yourself, your services, your expertise, etc.
The challenge is this: How do you get people to read about your profile without harassing them or, worse, spamming them? Simple: give away something valuable for free.
(Notice that free blog is my way of giving away something for free -- whether or not it's useful to people remains to be seen!).
In other words, as a professional, you certainly have the right to remain silent (about your talent, your services, your expertise, your experience, etc.), but it's definitely not profitable in terms of career policy. It's much better to speak up and tell the whole wide world what it is that you know which may be useful for them to know.