“A modest MOC system that is regularly used, and works is much better than an elaborate, sophisticated system with an impeccable paper trail that is occasionally winked at, bypassed, or sometimes totally ignored.”
Roy E. Sanders
The above is a quote from Chemical Process Safety, which I felt was a good explanation of the importance of a simple MOC system.
Basically, it comes down to the fact that you don’t want the system to be so cumbersome that employees look for ways to get around it. It should be easy to use and the paperwork should not take too much time.