No, he was asking who kept the wizard from dying to mooks in combat.
Oh! The party fought in its entire. That said, the Wizard was something of a paranoid and wasted a lot of power keeping defensive spells up when they probably weren't necessary.
Do Fighters and Rogues have value? Of course, I never meant to imply they don't. It's just that they literally cannot replace the spellcasters and succeed at the same range of missions. With care and forethought, spellcasters can get through reasonably short missions leaning on assets like defensive spells, summons and conjures, or hit and run tactics much more easily than the game allows non spellcasters to replace magic.
Part of the problem is in the more recent (3.5+) editions of the game, great care has gone into making certain all the classes are capable in the combat pillar. So dropping all non caster and replacing them with caster will change tactics, but maintain capability.
No such care has be given to other aspects of the game so travel, survival, and exploration are hard hit by the removal of magic.