It's funny how some people care about minute details of the gun. I personally know a retired full bird colonel who was airborne infantry all his career. He cares less about the gun itself. It's just a piece of equipment like the airplane he jumps out from.
It can be if it's of a known quality. I would not trust a number of AR's as a "piece of equipment", whereas others I would.
To comment on what an above poster said about some people dumping tons of money into AR's...
Well there are two types of people in my mind... those that shoot their guns and those that don't. With the majority in the latter category.
Every AR I build, I build with the mindset that it can be run into the dirt and then some. I'd bet the majority of AR owners on here don't have 1000 rounds through their rifles, some may not even see half that in it's lifetime.
Do I have thousands of rounds through all of my AR's? I wish. I have one in particular that has seen about 10K with a preventative bolt rebuild at roughly 8K rounds and occasional buffer spring replacement.
Everyone has items in their lives that are "black boxes". For some it's cars or computers, for others it's guns. It doesn't make it any less important that these items are quality and work when you ask them to.