The difference is that if you accidentally skip one of these steps, you won't destroy a $50M+ piece of equipment, devastate 100+ families, and/or disable an air

The difference is that if you accidentally skip one of these steps, you won't destroy a $50M+ piece of equipment, devastate 100+ families, and/or disable an airport or neighborhood for days while rescuers collect the body parts of all the people you killed. Complexity is the enemy of humans in stressful situations. Where lives and tens or hundreds of millions of dollars are on the line in a zero-fail environment, I would strive for simplicity.