Snipers need that kind of accuracy or better, not the average soldier or marine. Standard ball ammo is not held to a 1MOA requirement. You can qualify as expert in the military shooting much less accurately than 1" at 100 meters.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek