Chaotic Chao
horns Horns HORNS
http://wiki.srb2.org/wiki/NiGHTS_Tutorial
This is one of the reasons why if I am not mistaken, the tutorial needs to be rewritten and it is a time consuming task. It is to make it more understandable and more elaborate since making a great tutorial is hard to do on things like this and it takes time and effort as well.
The Nights Technical Document basically tells you how Nights Mode works, what objects are needed, and how each object is used in the mode as he stated in his post.
I know that, ironically.
The Why part was for his first statement, however.