The New York Times and similar newspaper websites have the “Share” button on their site for a reason: to promote stories and to encourage commentary. Once your content has been recognized in the social sphere, a byproduct of this promotion is discussion.
The discussion, as we know, is not necessarily positive. In fact, in some networks, it is often heavily biased. (On sites like Digg, saying “great site” really doesn’t bode well.)
Remember that a big challenge about designing a website or product is about not necessarily knowing what the end user wants. Your own agenda may not necessarily produce conversions that benefit you. You could ask your peers for feedback but they may not necessarily be as critical of your product offerings as you want them to be. An outside user oblivious to you and your offerings may be exactly what you need.
Enter the social sphere. At times, this criticism is really harsh, so this is not necessarily the practice for the faint of heart. If you look to improve, however, and you want that feedback, making an entry into a social network is a great way to get some good solid feedback.
Is this foolproof? No. In fact, it may not necessarily be helpful at all in some instances. But it may get you a little further than you would have been had you not “asked” for the feedback. The discussion and criticism might get you different insights into your product offerings than you wouldn’t have found elsewhere, and that can be extremely valuable.