I mean, the only thing he says that you could optionally do is the "-3 hit points thing". Otherwise, it's just smack dab in the text along with everything else in the DMG. I can't guess at his authorial intent, since he says both that the game is your own, do with it what you will and that if you're not using all of the rules you're not playing D&D.*
It's definitely less clear than how it was spelled out in 2e.
*Which I've heard was due to his fear of other people stealing all his ideas, but when I read the book back in the 80's, it sure left me confused.