Facebook changed when it decided its best source of revenue was advertising and that it would own the ad inventory (Google did the same thing, and with similar

Facebook changed when it decided its best source of revenue was advertising and that it would own the ad inventory (Google did the same thing, and with similar loss-of-value to users, which also devalued the underlying behavior the company depended upon for quality targeting). I think that Facebook's only real revenue option that would have also retained the fundamental value of the social network and its effects was to behave either as a third-party sentiment/preference analysis service ala Nielsen Ratings or as a source of ad targeting for individuals (based on their sentiments/preferences expressed within FB) that could be sold for use external to the FB experience... and I have suspicions that even the latter might have eventually led to distorting that core FB experience. The social network and the behaviors within it were only truly valuable if externally observed without intervention. By pushing behaviors that FB itself wanted users to perform they broke the uniquely valuable part.