WAIT - maybe I'm thinking of something else. Is it possible that they disallowed the ability for, say, +3 to Fury (Barbarian) and +5 to Arcane Power (Wizard) on the same item? That must be it, because you get zero benefit from those, at least the primary stats are doing something.
No, those are not primary. You're thinking of the days before strength, dexterity and intelligence. Back when they had things like precision and attack or something similar to that. There were awkward combinations of attributes that didn't quite make sense.