"One key to understanding Gygax and HIS 1st Ed AD&D is that he took a phenomenological approach to DMG writing. His DMG is a collection of essays which describe game mechanics for different aspects of the game. The articles themselves are not bound under an overarching "Core Game Mechanic" of the WoTC editions. This is what makes his version of the game superior, since you can write a section of rules to describe any aspect of fantasy role plaing, and not be bound by any pre-existing game mechanic or a process."
I disagree with his further comments on Non-weapon proficiencies, but there you go.