“IF YOU’RE A PLAYER, DON’T READ SECTION #5”.
Among all advices written in rpg books, this one deserves the award of most retarded one. Why? There are many reasons, but the most important one is that plenty of times people can’t predict whether they will play this game as GM’s or players. Even more: people can’t predict whether they will play this game at all. Asking to not read something is like “hey, bro, read the Lord of the Rings saga, but remember to skip the Hobbit, because there are things out there that will hint you about stuff and that will ruin your fun“.
Come on! How about you write the book in such a way that the knowledge of stuff won’t change a thing?
“But that’s impossible!” Yeah, right.
How about the approach presented by KULT or Trail of Cthulhu ? You know, “here’s the set up and here are a few different explanation for how things are“.
It’s actually very simple trick. And it works. So what that players will learn one of possible explanation? Or all of them? They can’t know which one their GM follows and – that’s even better – to which extent.