That's not even.
There's exactly one player in the left column who would crack the top 8 in scoring on the Sharks.
I agree Hertl has the better forward teammates but it’s not quite the gap that you may think it is. Their current lines are Kane-Hertl-Donskoi and Kreider-Zibanejad-Zuccarello. That winger support is pretty much dead even. Their forward support outside of those current linemates tilts things in Hertl’s favor, but...
It also helps Zibanejad because it allows him to play far more minutes. Zibanejad has played only 4 more games than Hertl, but he has played 125 more minutes at even strength. Hertl averages 14:15 ESTOI/GP, Zibanejad averages 15:28. Yet, Hertl scores 3.32 even strength points per 60 minutes (5th among centers) and Zibanejad scores 2.35 even strength points per 60 minutes. (35th among centers)
The area where Zibanejad makes up the gap in production is on the power play, but again, I think those weaker linemates might actually play into his favor there as well. Hertl is primarily the net front trigger man on a power play where he doesn’t touch the puck much if he isn’t shooting it. The results on the PP are clearly satisfactory - the Sharks PP is 5th in the NHL, Hertl is 5th on the team in PPTOI and tied for the team lead in PPG. Hell, Hertl is 11th in the whole NHL in PPG/60.
Zibanejad, meanwhile, is far more productive on the PP - scoring slightly more goals and way more points. Zibanejad’s actually one of the best PP producers in the NHL per 60. But Zibanejad has the benefit of the Rangers PP running through him, while Hertl does not. That doesn’t mean that Hertl could successfully run NYR’s PP like Zibanejad does - I don’t think he could - but it definitely helps Zibanejad that things are set up that way.
So, in summary, the teammates argument can go both ways.