Project managers use checklists to estimate and control projects. Pilots use checklists to prepare for flight. Scuba divers use checklists before going into the water. Everyone uses lists for the same basic reason. We all recognize that when we are preoccupied, under pressure, or distracted, we forget things and make errors in judgment.
Lists are like the rules that the Mount Everest climbers imposed before their climb.
We need them to simulate good judgment at certain critical times. We instinctively use lists for survival. In a development situation, you or I might choose not to do some task in a standard because it might not be appropriate for the project or organization. In many modern standards, the only mandatory activity is tailoring the standard to your particular needs. Modern process standards are not designed to replace professional skill or experience in software development.