If you built a scale model of a good egg drop rig for the size of a person would it protect them from jumping off a building without breaking anything?
With an egg drop, you pretty much just have to worry about the integrity of the shell, but with a person there are a lot more factors at play. The first example I can think of off the top of my head is in MVAs. Modern cars are designed to absorb a lot of the momentum from collisions and minimize injury to passengers, but that isn't always enough to save lives.
You're not a solid body. You are basically a big blob of salt water that happens to contain some hard bones and ligaments mixed in with vulnerable organs. Even if you can protect the blob, those organs can still move around inside it.
Let's say you slam into another car head-on. The frame of your car absorbs a good bit of the energy, but your body still "wants" to keep going forward. Then your seat belt stops your thorax, but your heart and major vessels keep going and slam into your ribs, sternum, etc. Best case scenario, you'll walk away with a minor myocardial contusion and possibly develop a dysrhythmia, but if you're not so lucky, your descending aorta may actually be ripped by your ligamentum arteriosum and you'll mostly likely bleed out.
Your head isn't as restrained as your thorax in a car, but even if it were your brain can still move around and slam into your skull (which can lead to traumatic brain injuries like concussion, diffuse axonal injury, cerebral laceration, etc.).
Part of the reason why you can't just take the egg result and scale it up is called the square-cube-law.