Muhamad,
The PMP exam is NOT a test of the PMBOK Guide. The PMBOK Guide is only a reference book to help you prepare for the exam.
Instead, the PMP exam is based on The PMP Examination Content Outline and you can find this document here:
www.project-management-prepcast.com/pmpoutline
-- In essence, this document describes the topics that you may be tested on during your exam. Please review it and you'll see that "benefits" is mentioned.