Both companies use the argument of don't put it on the Internet if you don't want everyone to see it. The problem being that both companies make their profit by people putting to much information on the Internet so I feel they are disingenuous since they want to keep track of as much info as everyone as possible.
The real problem is with more and more life being lived online. Unlike real life past actions on the Internet sticks with you forever. Luckily my childhood is pre Internet but kids growing up right now can have their childhood haunt them. (And yes every child does stupid stuff that they learn from.) Even adults have changing opinion over the years. Having every opinion tied back to you could cause problems later (and is the reason why a lot of stuff and names are vague here.)
Using information from the Internet can create new types of theft too. Most cell phone cameras post GPS locations of the photo taken. with websites like flickr having image recognition all a burglar has to do is search for what they want on flickr, take the GPS coordinates from the picture, wait until the person posts on foursquare that they are away from home then stop by their house. Other people might just want to track when the parents are out but the kids are home. As someone that works with trying to advance technology every day I know this seem hypocritical but I just don't think that society is able to keep up with how the Internet is changing social interaction.