When a DM can't judge difficulty by eye, this system doesn't help. He still needs to work out "situational modifiers" by eye. It's the same problem under a different name.kreynolds said:Quite frankly, because some people can't eyeball CR, or even EL, worth a darn.
If there were a comprehensive list of all possible situations and modifiers, then the system would be of use to those DMs. It would then be too unwieldy for common use.
(Example: If some of the party has fire resistance, another is fire-immune, and half the rest have SR, what's the situational modifier against a fire elemental? Against a water elemental? Against a monster with lots of spell-like fire powers? If the fire-immune PC also flies, do the modifiers stack when facing a nonflying melee-only fire creature? What if that nonflying creature has a spellcasting ally with access to fly?)