Except hall put up more points on the pp where hischier wasn't even on the pp. Let's not attribute halls 40 point bump Soley to his hischier because that's ridiculous.
Hall has scored at ppg pace before, let's not pretend he's a scrub. Primary points / 60 is a very poor indicator of performance when you only have this as a sample size. Yakupov primary points /60 was higher than MacKinnon and Matthews in their rookie years. It also says Dadonov was 4th in primary points / 60 last season with minimum 60 games played. Barkov had his best season last year.
They both benefitted from each other.
I doubt you have the time, but a fun exercise I always like to say is look at all of Hischier's goals and look at a video of all of Hall's points last year on youtube.
Their impact on each other was pretty even when you go back and watch that, I'd lean more toward Hischier impacting Hall more than the other way around. Their success was a lot more mutual than people anticipate. It wasn't like Hall was gifting Hischier wide open nets every night, a lot of their mutual points were off of terrific plays by both. I wish there was a video of all of Hischier's points because that would be an even better indicator of Hall's impact on Hischier and vice versa.
Obviously, there's more than just goals and assists there, but I think it helps to break the notion that Hischier's success was largely Hall's doing.