All of which can be massacred by you, even so your missing the point. They have the men necessary to do the jobs that are currently being done. But no more. And the jobs your sent on have a risk of a high casualty rate.
Nope not missing the point.
The point imo was that it seemed weird that they sent you to perform carry quests because they were too difficult.
Some pointed at that the PC was favoured by special rules as unique, I pointed out not so much on that point.
The simple reason ( sorry the point ), is that if they had the NCR do it themselves it would make a short game.
So they add flavour and make it seem like you're special, and are capable of cutting through red tape...
I.e Ranger Morelas.
Forlorn Hope.
Mojave Outpost.
Ranger stations.
Bounty missions.
The only truely unique parts they need help with is directly dealing with the legion in espionage.
Edit: Sneak if npc's could sneak just like the pc then the difference would be nought.
As by far and away only sneak attacking and player intelligence makes a difference.