Once you become known as a skilled manipulator fewer people are going to trust you and fewer people you can influence in the long run.

But it seems that people who use the Dark Arts profit from it. If the Dark Arts were self-defeating as you suggest, we wouldn't be having this discussion.

Using Dart Arks is a Prisoner's dilemma defection with all associated problems - a world full of Dark Artists is worse than a world full of honest truth sayers, ceteris paribus.

Continuing to cooperate in a world where most players defect is a poor strategy. I also doubt that it strongly influences the defectors to stop defecting.