For me, having my own data all in one place, cross-referenced and easily queried is exactly what I want. It's convenient, useful and valuable to me, because that makes it easier to use. Unfortunately, having all that data together and easily-queried is just as valuable for anyone with access to the data, including identity thieves, spies, marketers and unscrupulous government agencies with too much power. So when I'm dealing with a corporate or government entity I can't trust, it is better for me to have all my information scattered, difficult to retrieve, error-prone and out of date. In other words, for myself, I want Facebook to expand and expand until it is the only online tool I ever need. For the NSA, I want Facebook to shrink, stagnate, fragment and die, because otherwise they will end up using it against me. That data is power, and I do not want to give over that power where it may (will) be abused.
Mokalus of Borg
PS - Some would argue that governments naturally produce error-prone, out of date, scattered data.
PPS - But even that can be dangerous.