@
Manbearcat - one moral of your posts is that there's no uniform thing
good GMing (and hence no uniform thing
jerk GMing). This can be set out in terms of both
risks and
skills.
An obvous risk in GMing AD&D in a non-class dungeoncrawling context (and 2nd ed AD&D really brings this risk to the fore) is railroading/"Mother may I" - because the system simply lacks a mechanical framework beyond
GM decides for making important decision about the fiction outside of combat. We can see this in the orc cannibilism chase situation: AD&D barely has the mechanics to determine whether or not the PCs forgoing rest lets them catch the orcs (at best their are movement rates, but nothing for determining whether eg the orcs get slowed by a flooded creek or twisted ankles), let alone for determining how frequently and how many children the orcs eat.
That particular risk simply doesn't arise in (say) Burning Wheel, which has robust mechanics for resolving an indefinitely wide range of conflicts.
A risk that arises in classic ("skilled play"/dungeoncrawling) D&D is that the GM lacks impartiality and "gets involved". And the flipside of that is that a good GM for that sort of game
need the skill of remaining impartial and impassive, and of judging what's the proper amount of information to communicate so as to keep the "free kriegsspiel" going but not just telegraph the solutions. As I've often posted, it's a skill I lack.
Conversely, my love of
getting involved - of taunting and poking the players and seeing how far and in which direction I can push them - which would be a liability if I was running a ToH tournament, is a virtue when GMing Burning Wheel, or Prince Valiant, or 4e. It let's the players know what I think is at stake in a situation, gives them something to play off and push back against, creates conversations in which they can correct misapprehensions if they think I've made them, etc.
That's not to say that there can't be multi-purpose systems. A lot of people think of Classic Traveller as a game to be GMed by an impartial referee. But I'm finding it to be eminently playable in something closer to a DW style (and even in the original, 1977 rulebooks there are passages that point in this direction, like the observation (Book 3 p 19) that "in many cases" the referee "has a responsibility" "to impose encounters to further the cause of the adventure being played").
But most systems tend to foreground one set of skills and techniques and make some other approaches a liability. A strong sense of
how things will unfold is pretty crucial if a GM-driven, 2nd ed AD&D type game is going to reliably produce strong story - if the GM doesn't bring that to the table, then in the absence of mechanics that will reliably deliver it, or player authority to do it, where's it going to come from? (Hence we get the typical AD&D 2nd ed era, CoC, etc module design.)
But briniging that inclination to the GMing of (say) a DW game will just cause headaches and heartaches.