I think it can be revelation for some guys.
I know in the 90's, pre internet, back in the dark ages, I'm sure many guys on this site were absolutely clueless around women. Couldnt have even imagined something like the dj bible being available.
Another thing that it can do is shorten the self improvement process. I use to be in all kinds of crazy stuff (even ordering pheromones from the internet, they're suppose to give you a scent that makes you irresistible to women). You dont need all of the dj bible to be successful, but still has some excellent points that are useful.