Z is and always has been more impactful. The team always plays better when he is the focal point, which is what they've been doing since he spoke out.
I’ve seen the team rally damn near the same when he was out too. Like when he went on that 7 game win streak early last season when Ingram was out, they went on a similar run late in the season when they won something like 8 out of 10 when Z was done
I agree Zion has a certain level of dominance in the paint that can’t be replicated by anybody else in the league. But when they go against defensive squads with length that key in on him he can be limited in a half court setting. He still has areas of his game that needs expanding and I’ve seen him do it to some degree this year
Those limitations is where a 3 level scorer is needed that can score mostly anywhere in the half court, is at least elite in one area of offense, can play make at a high level, shoot, and get to the line comes into play. That’s BI’s role and often times he’s the closer just as much as Z
They really are a more modern diet iteration of Shaq & Kobe