Because both things don't belong to each other. IQ helps you anticipate and understanding where the play will go. Passing vision is just that, you often do this prepared in your mind. "Oh, X player is coming up on the net and the defender hasn't pivoted yet. I will make a pass".
It's reactivity vs proactivity.
This is both overly simplistic and an incorrect way to describe and or understand "reactive vs proactive" decision making in sport performance.
Proactive decision making can better be described, and observed, as the often small and nuanced physical adjustments performers make that allows them to collect and process greater information as they navigate their dynamic environment.
Reactive desicion making is when players act without full information, relying instead on anticipation (elite performers ) or hope/guesses (weak performers) to execute...
High IQ players would better be described as those who make higher percentage decisions, both proactively in putting themselves in optimal postures and positioning, and reactively in effectively anticipating via instinct/experience, more consistently than others ... that applies equally to proactive or reactive actions.
There's a ton of great literature on this, in particular on the ways to develop motor learning and performance.
Interestingly, what the Habs did with Slaf from the start was very aligned with the best research out there... And the outcomes this far match what a person familiar with the lit would recognize... Namely the dip in his performance as he rebuild fundamentals, the superficial appearance of "slow" processing, and the lack of fluidity in his movements.... Followed by a rapid upward trajectory as the new motor skills became imbedded and he was once again able to tap into both his immense physical attributes and his higher end processing (ie decision making, ie hockey IQ).