I don't think the implication that only "bad" people can be blackmailed is valid. You could be blackmailed for being a homosexual in many parts of the US still or doubting the existence of god or having unacceptably conservative political views. We do all sorts of things that are not at all wrong but may carry a significant social or economic cost if they were to be exposed publicly.
I think people are overlooking this. It can even be worse in other countries. Some of those things (among numerous other things) can lead to death in a few countries.
