How I’d look at it is that teams can utterly destroy QBs, even top tier talents. Yes the makeup and personal qualities have allowed those like Brady, Mahomes, and Allen to become Supermen. But I don’t think that is inevitable; you can break a QB either through killing their motivation or steering them the wrong way. If they go too far learning wrong then their odds of success dwindles significantly.
Josh Allen on the Jets likely flashes greatness for three years while struggling to find a groove and then is jettisoned as a backup candidate elsewhere. His inner- drive might save his career but he likely never reaches the Allen we know. Once he’s out of the Jets he won’t have the advantages of a young QB getting ample opportunity to learn and make mistakes because he’ll just be a backup “Hail Mary” idea. He’d likely become what Sam Darnold is; a reformed starter who could have been great but ends up falling short. Allen/Mahomes/Brady can work tirelessly but if the team doesn’t give them proper support it won’t matter.