Prophet of the profane (She/Her)
Now I'm thinking about it, maybe fairness and bias are secondary concerns.It feels here like the idea of referee is not finding any purchase in your conceptual framework. So it is quite hard to explain anything further about that.
Perhaps one can say something like - Given I believe that GMs are unfair and biased, I ought not to preference GM'd modes of play that rely on fairness and impartiality. That's not an irrational position, even though I disagree with the premise.
Expertise (or, rather, complete lack of one) is more important. Let's say I'm running a game where PCs are officers in the orc resistance, defending from the invading armies of the Iron Kingdom. They come up with a plan to harass supply convoys of the invaders to halt or at least slow down their advance.
Will it work? I have no clue! How does the Iron Kingdom protect their supply routes? Do they even have established supply routes, or every little lord handles their logistics separately? Maybe they mostly rely on marauding nearby settlements? What is their military doctrine? I don't know! And I'm not even remotely qualified to make one up, on the spot or before hand, because my understanding of medieval warfare is close to non-existent.
My judgement of this situation will boil down to "yeah, this sounds smart". I'm not qualified to test the players' skill at repelling imaginary vaguely medieval army (there are people who certainly are, but I'm not sure if 100% or even 10% of GMs are experts on medieval warfare), so the only skill being tested is their ability to please me.
Replace "repelling imaginary vaguely medieval army" with "traversing trap-riddled dungeons full of monsters", nothing of matter will change.