My guess is that the situation is something like this.
Many of us think of this site as a private, intimate community where we can in (semi-)anonymity discuss difficult personal goals and receive the support of a like-minded and relatively small group of people who are doing the same.
The owners of the website think of the site as giving us a free way to track goals and help each other reach them, but in public. The more public the better. Privacy, anonymity, limited audience does not appear to be of primary concern.
We’d like to be able to have fine grained privacy controls to limit who can read our entries. I strongly suspect that the robots would like to see something we write go viral on facebook and draw many visitors and new users to the site. I think of the entries I write as belonging to me, personal and meaningful. I think what I’m doing, though, is writing free content to attract page views for showing ads, and that was ok with me because these things were not completely in conflict.
I am not at all happy about the facebookization of the web. There are facebook trackers on virtually every website and aggregator sites like AddThis (which is what 43things is using) that are designed to make targeted advertising more efficient. The problem is that the more centralized the tracking source (such as facebook), the more they know about you, the less privacy you have and the more that information can be misused. I can foresee a time when my insurance company will know what articles on WebMD I am reading because facebook will have sold it to them (tracked by the “Share” button on WebMD articles (yes, there is one)).