Why is the Prima Guide based on hard difficulty?

I recently got the guide for Black because I can't be bothered to remember the locations for all of the Gold Scarabs and Lives of the Gods, nor do I want to constantly scroll through forums on Gamefaqs that list everything mostly correctly. Something I noticed however is the fact that a lot of the information provided is stuff that only appears on Hard mode. The 2 white ninjas assisting Murai and the Doppelganger fight in the monastery only happen on hard. The Gold Scarab rewards are also based on hard mode as you don't get the Plasma Saber Mk. II on normal/Ninja Dog. Admittedly, I do prefer to play the game on hard as it nets me cooler rewards and has better enemy variety, but this guide was likely made for complete newcomers to the game who are DEFINITELY playing on normal. There's even an ad for this guide in the game's manual. Prima Games is known for being inaccurate, but this is a really weird way to be wrong.