They are 2 different types of balance
I do not see anything resembling an argument for delineating balance against the environment from balance between players here. What makes another player distinct from an environment if both are bound by the rules of the game re: game theory?
Even if we argue case and not type, you are aware that hostile NPCs will have levels in character classes, correct?
your argument fails to show that you cannot balance a game against the environment by simply allowing the environment to also use the "broken toys."
I think maybe you've gotten confused. And the double negative is confusing me a bit here. But if I understand you correctly, and that's a pretty big if: This was not the intended purpose of the argument and I'm not sure how it's relevant here. I was demonstrating that balance - here meaning complexity or obfuscation of player means and goals such that all means approach equal purpose towards goals - is critical to the design of cooperative experiences.