I feel like at the end of the day a debate on any art form, when given enough time and energy, will always devolve into "relativism vs. empiricism," and trust me I've already been made to sit through way too many hours of art school students and professors literally screaming at each other, sometimes nearly coming to blows, about that very topic, while all I wanted to do was go back to the studio and work.
Here's an idea: how about we ask the relativists to let the empiricists try to do the work that empiricists think they can do in peace rather than being screamed at by relativists? If the empiricists are wrong their own work should eventually do a good job of demonstrating it. If it's all fantasy then what's the harm in letting them fantasize in peace?
Personally I feel that the "nothing can ever be said to work better than anything else" position is far more aggressive than most theory ideas I've seen articulated, and it's often tossed around without any of the "I feel that..." "It's my opinion that..." "I could be wrong, but..." caveats that anti-Theory people often insist on from others. I think it is fundamentally anti-game-design: If I make a change to a game I'm designing that I believe makes it "work better", are you claiming that I'm deluding myself, and that neither version works better or worse than the other? It is not an intrinsically friendly, neutral position, it is making strong claims.