GMMichael
Guide of Modos
Quite possible that non-D&D core books do this. Think about it for a bit, and you'll realize that GMing advice could easily take up 400 pages or more. This wouldn't leave a lot of room for random magic item tables, which I think is why D&D limits the content.But I'd still like to see our core books say, "But you know what? Here are these other game parameters and these are the means by which you might accommodate them."
To me, the GM has too much on his plate. Even when he has computing tools to help. So player jobs just make sense.