Because certification confirms an understanding of a common body of knowledge. This will reduce the time it takes to find and train someone because everyone who is certified already knows the best way to do something. Many certifications, such as the CCMP, also confirm experience. It's a way of ensuring someone doesn't just learn a few buzzwords and doesn't know how to actually do the job.

Certification enhances an individual's and an organization's reputation. Any time you get to add letters after your name on your resume, you increase your value, and when an organization adds certifications, it increases the overall knowledge held by its employees and reduces the risk of doing something the wrong way, thereby causing schedule delays and cost overruns.

While a certificate provided at the end of a course shows the completion of training, certification shows a deep understanding and retention of the material and proves it with a third-party proctored exam. Any person or for-profit organization can provide a certificate. The ACMP, though, is nonprofit, which eliminates the monetary motivation to get as many people certified as quickly as possible.