The gun is the tool. You adapt it to you, not the other way around!
For many people, the stock in the pocket, cheekbone on the "comb" and eyeball on the same axis of the sights won't happen correctly with the typical configuration. That is why, at least in the last decade, there are so many new stocks with adjustment. If you look at all of the top competitors using the AR15, they have adjustable or custom made stocks so that the NPOA and fit are correct. Especially when shooting optics at ranges past 200 yards, parallax becomes an issue if the eyeball is not on the same axis as the centerline of the optic. There are a lot of good options, from $50 to $300 for adjustable AR stocks (not talking just about length). ALL of my ARs that are used to shoot past 200 yards have a stock that fits right, or is adjustable to ensure proper fit. Having the stock IN the pocket (yes even with the low recoil .223) allows you to shoot faster, transition faster and have more accuracy. The photo Lindenwood posted is terrible fit, but with a red dot and close targets, you can get away with it...a tad slower, but not a huge deal. If you are just plinking 200 yards and in, it does not matter as much.