Yup, get more bang for your buck. +1 conviction gives you the exact same damage as +1 discipline, but +1 discipline also increases your chance to hit.
While true, what makes wizard spells insanely powerful is the ability to add "outcome" shifts by just taking more mental stress. Why reserve all the fun of that to non-rote spells
. Yeah, you want to crank that discipline up there, but you those higher boxes on your conviction stress chart are like free "bang" as long as you aren't so far behind your discipline that you start taking consequences making use of them when drawing power.
I mean, wizards ALSO can get a +4 to hit with a focus item, where the best a stunt can add is +1. But the equivalent of just drawing an extra 3 power over conviction (checking 4th stress box instead of 1st) is a stunt AND a fate point (Deadly Blow). And you can do both, with no extra skill investment needed beyond lore to improve the max quality of your foci.