Come on man, you're way smarter than using Per/36 in any serious basketball argument. I've been over this what feels like 1000x on this forum, but it's just a worthless stat. Doesn't tell you anything.
And no, not every big, but when you're an absolute liability on the defensive end, you better be an offensive savant in multiple ways to make up for it. Which is why a lot of this discussion is a moot point because even if Bagley could get to being an above-average scorer, he gives it back on defense. Bagley has been one of the worst ball-stoppers in the league the last 3 years. The possession often ends with him, which is why his lack of creation matters because along with inconsistent shooting, it's another fault you have to account for when he's on the floor.. It'd be one thing if he were an elite scorer/finisher in the vein of a Zion, but he hasn't been close to that thus far.