I think that every one pretty much has more or less made excellent points without the garbage throwing on this topic that occurs on some other forums. Bearcreek is probably accurate in that most folks buy an AR for more or less a range rifle or because it might be banned or some other such reason. I think that it is fair to say that more people probably go through handgun training than for long arms and even fewer probably go through long arms tactical type training in the dirt, rain, etc. Henderson Defense in that famous long AR thread, even indicates as much as the folks going there fire mag dumps at relatively close range but they are not playing Audie Murphy when doing so. Others are chiming in with their real life experiences with Bearcreek products and most seem to be satisfied with their purchases.
As a personal disclosure, I assembled uppers using Bearcreek barrels and they were acceptable enough for what I bought them for. One was for an AR 7.62x39 pistol upper and I had no desire to build an accurized $1000 upper for an essentially crippled AR without a stock using blaster quality steel cased ammo. After what happened with bumpstocks, I really did not want to spend a lot of money for something that I might have to get rid of.
The other was a cheap bone stock M4gery 16" barrel using iron sights. I have no desire to crawl around in the mud, cold, etc. as I have been there and done that and the M4gery functions well enough for my 2-3 MOA expectations using range fodder 55gr ammo. If I did, I have other AR's to do that with. On the other hand, Bearcreek had a period a few years ago where apparently some folks on forums reported that they had some issues.
AR's and their parts are one of those things that has become a commodity. Nitriding barrels used to be extremely expensive, now it isn't. Quad rails used to be the price of budget bolt rifles, now they are in the remainder bin at Numrich, and so on. For awhile, chrome lined barrels were very expensive versus chrome/moly as were stainless steel barrels, both have come down in price related to chrome/moly. Triggers ditto.
AR's have essentially become a mass market item compared with twenty years ago or so. Thus, to distinguish themselves (and to get a higher price for their goods), all sorts of distinctions by manufacturers are made, some are cosmetic, and some are not. Some aim at specific niches such as 3-gun competitions or using non-standard innovations such as POF. Other sellers aim at the low end of the market where something usually has to give to some extent, in some cases it is fit and finish, advertising, and service. For other makers it may be that critical parts such as barrels and bolts may vary more in quality, and the cheaper may be using generic parts from the lowest cost supplier (usually from China or thereabouts). I see the same thing in the computer industry.
The major issue, assuming no actual faulty parts, is the quality of the assembler in making a rifle work. Knowledgeable folks willing to do some handfitting when assembling themselves or returning out of spec parts or rifles, can get a functioning AR rifle for cheaper than the "brand names".
Those that do not want the hassle factor can buy name brand and pay the freight and return the sucker if not perfect. Those that want a rifle to excel above and beyond the generous military accuracy std. and function usually for a niche function such as 3-gun, combat type training, or long range shooting, will usually have to pay for what they want.
And so it goes where you place your bets and take your chances.