What you say isn't something to hide, it's information you can use against me if you are able to hide how did you use it.
But if i can know who tries to access my account anytime, i don't need that password in the first place! Try doing something fishy, and i'll track you down:)
Everyone on the internet has something to hide, and that's their passwords. The problem with the "use normal information for blackmail" case is that its very difficult for the public to understand.
They often have never been bullied, and don't have the imagination where they can see a point where normal conversations can be used against them.
The bank account argument is far easier to explain and grasp
Also I'd like your significant other's mobile number. I'd like to see if I can get a topless pic.
Everyone has something to hide.