Hey, great to hear you're enjoying my game! Well, there *might* be Wizards who, for some reason, can't cast spells per se, but have powers that mimic spells... for instance:
A Wizard with arcane protection ("arcane armor") who is able to enhance the effects of magic items simply by touching them. This Wizard rolls two spells: Sleep, and Shadow Walk. Now, we know s/he can't cast spells (because the player didn't pick or roll the move "1. Cast Spells"), but somehow, this Wizard still has the ability: maybe it's a PSI-like thing, or maybe those "spells" are beings he tamed.
The difference is in the narration, and it's also in scope: A Wizard without that move "1. Cast Spells" can't learn spells from a book, in my game. In your game, of course, this might be perfectly possible.
Does this make sense?