Some people are willing to spend more money in exchange for a higher quality firearm. The concept of "with Colt/Noveske/BCM etc you're only paying extra for the name" is mostly a technique used by some buyers/sellers to convince themselves/their customers that the consumer-grade price-point rifle that they're buying/selling is "just as good as" the more expensive Colts/Noveskes/BCM's. It is true, however, that those $600-$800 rifles may be "good enough" for many people's needs for that type of firearm. Think of them as the Jennings/Hi-Point/Bryco/Ravens of the the AR world.
Melonite is a cool idea for a gun barrel. I do note that many gunsmiths either won't do any drilling or pinning of nitrided barrels, or they charge extra.