It's common to confuse the Peter Principle and the Dilbert Principle, but they are not the same. In fact, they are nearly opposite to one another, despite producing similar outcomes. The DP proposes that those who have shown themselves incompetent are promoted, either to get them out of the way or because the competent people are needed to do "actual work". The PP proposes that those who display competence in their current work will be promoted until they reach the point where they are no longer competent. Notice that the PP assumes that higher-level jobs are harder or require rarer skills, while the DP assumes the opposite.