I agree with Rich.
A neck is the sum of it's parts. Wood acts like wood. Flat or quartered, both have their own characteristics to deal with. In my experience a thick board will warp more during the shaping process than a thin board. That's not to say every thick board warps, it's just more likely. Hence, using the lamination concept decreases that chance more than a one piece neck. It's kinda like driving, sure you could roll through stop signs but that might increase your chances of an accident as compared to routinely making a complete stop.
Something to consider here: Fender, Gibson, etc. buy HUGE quantities of stock. With that comes the power to dictate just what sort of stock they receive. There is no doubt that they are selective with the lot.
-Doug