I am no expert on AR's by any means, but you are spot on here.
One of my workers knew I was into guns and knew I tinkered with AR's. He told me about starting a build and I really tried to get him to let me help walk him through the 1st one. I offered to let him use my tools, supplies and would let him do the actual build, just wanted to walk him through it to make sure it worked correctly.
Well, he didn't. He said he watched plenty of YouTube videos on it and knew how. I got pics of it though. Flash hider has no crush washer and tightened up upside down, bolt catch roll pin is only 2/3 of the way installed with idiot marks on the receiver, sights on backwards, and no staking of the castle nut. Not only that, he installed the barrel without a torque wrench, so its hit or miss if its installed at the min 35 ft/lb or not.
I get the same frustration with this kind of stuff when people ask me about what car they should buy (I use to sell them and buy and sell alot on the side). Then they turn up in some piece of shit Dodge Journey and wonder why the car is in for warranty work so much. I digress...