What I had found instead were biases that seemed to be injected by the "role: system" instructions.

Well, we need Intelligence (Pandora's box is open, now we need the Real Thing urgently). Typical (aggregate) positions, dumb as expected, will be overcome by a Reasoner. (And I can say, already a number of LLMs can reason even when they start from cretinous aggregate positions if you give them the proper freedom of assessment.)