I think I can summarize No Child Left Behind succinctly:
No Child Left Behind Leaves Every Child Behind.
I think it is the same attitude that every child is a prodigy, every child is above average, every child is perfect, no child is beyond help. Some children just will not make it. My parents have a saying: "Someone needs to dig ditches." And everyone who does manual labor, etc like that grew up as a kid somewhere. Either by circumstance or by ability, some people end up doing that, while others excel and do more intellectual activities.
The world isn't perfect or fair. Legislating it is not, is not going to change that outcome.