Sorry, but you just haven't been paying attention if you haven't seen a single negative comment regarding the offense that wasn't about Martinez. People have been hammering the o-line (Jurgens for snaps, various players for poor technique and effort), Austin, the OC's, McCaffrey for his awful passing and whacky fumbles, Frost (for playcaling, game management, etc), WRs for dropping passes (including in the EZ) and pretty much every element of the offense when it sucks . . . and it has sucked in far too many ways and for too long.
I know you like to trot out AM's completion %, but you ignore that a good chunk of that comes from passes either behind the LOS or near the LOS. He was 81st in avg yards per pass (7 yards). NU has been pretty awful pushing the ball downfield--McCaffrey was terrible at it and AM is erratic for the most part. AM has also been in the top 10 nationally in fumbles every single year. He has to stop turning the ball over like that.
Everyone and everything on the offense needs to step up. And yes, that includes Martinez.