Blackmail material is only powerful as a threat. Releasing material from it makes the remainder less powerful. If you raise the stakes a little by adding some small details, an association here, a plausibly deniable link there, you can enhance the fear of the person on the other end of the blackmail without ruining the value of what you have. So depending on what people want they can get better results by keeping that information hidden.

On top of that most people who get dirt on one person get dirt on many people. You may want to take down one person but by if you release some stuff from the files then someone on the other side can burn people on your side. Mutually assured destruction will paralyse everyone.

As an outside to everyone I want all of it released because in my mind anyone implicated is either an active predator or someone who tolerates predators. But if you have paid good money to have a specific member of congress get into office and they are able to act in your favour then it doesn’t matter if they have a D or an R, they are yours. It is very expensive to get someone who understands the game into office and under your thumb. Much better to prevent the whole system from becoming unpredictable due to lots of sudden new blood and to keep known actors in place. Members on both sides of the aisle want the files locked away forever, meaning they want to protect predators. The failure to act is a choice, not an accident.

To be clear, I am including foreign actors, massive companies, all sorts of people. If you have an asset that can protect another asset without knowing then you generally would do so.