Information can be used in different ways, tracking information for the purpose of specific marketing to an individual can be useful.
The same information can also be used to harm an individual.

Complete privacy can on the other hand leave us isolated.
Generally if you are not a criminal you have nothing to fear - mostly, there are also bullies that will find something to pin on you whether you have wronged them or not - projecting their own pain.

It's one of those things where a little bit used in the right way can be helpful but used in the wrong ways can be harmfaul