Who knows?
Anyway, a debate on Nu-Metal is like debating how to get the leg off a cow. You'll end up going round in circles, eventually.
One definition of "Nu-Metal" is a band that lacks:
Talent
Solos
But makes up for it with things like:
Rap Vocals
A Turntablist
Samples.
A good example of a Nu-Metal Band is Linkin Park.
HOWEVER, there are many versions of Nu-Metal.
The 1st Generation of Nu-Metal would have to be Korn, circa 1994. Their downtuned guitars, and "scat" like vocals were something new in the music world.
Then along came the unholy one, commonly referred to as The Durst. His band Limp Dic... I mean Limp Bizkit filled every criteria for "Nu Metal," creating the Second Generation.
Then along came Slipknot. Their first album was nu-metal, but their newest album was something different..
Simply, You can't really debate on the Meaning of Nu-Metal, because Everyone has a different understanding on it.