This. It's the most important thing to stretch by far. One can definitely argue about whether or not people using Facebook should be allowed to complain that they are giving their data to them.

I do not use Facebook. They still try to get my data.

Well, they would if they could, and wouldn't be shitlisted by at least four layers of filters (NoScript, Ghostery, AdBlock, RequestPolicy). Still, I can't block Facebook trying to get people to identify me on photos I might happen to be on. While pretty much anyone I am closer acquainted to knows that we'd be through if they'd ever put pictures of me on Facebook, I can't control this for obvious reasons. I can't control photos taken of me on, for example, concerts, either. It's this loss of control that worries me the most.

What I am also concerned about is the fact that people who are not aware of the dangers that Facebook poses might learn one day - and then there will be no way to correct their mistakes anymore.

Finally, I am deeply anxious about the future of the net if stupid ideas like the Facebook login gain traction. I don't want to see a web where Facebook or Google are mandatory to do anything useful. It's already extremely disturbing how much of the net runs on stuff made by Google. This amount of dependency on a single, commercial entity is insanity, no matter how persistently they might insist on their "Don't be evil" policy.

The fun thing about tags is that you can't remove them unless you join Facebook. And one of the complaints is that removed tags aren't removed, but made non-public. These two points are raised in complaints #3 and #11:

http://europe-v-facebook.org/Complaint_03_Tagging.pdf

http://europe-v-facebook.org/Comlaint_11_RemovalOfTags.pdf