"...where the reward is for a correct answer..."
AI has no concept of reward, AI does not seek or desire and it cannot be incentivized.
"There's no effort taken to ensure that it got to said right answer in a morally defensible manner."
AI has no concept of morals, all manners to arrive at an answer are equally defensible.
"So we've been, more and more, progressively encouraging the creation of highly-capable immoral cheaters."
For an AI there is no cheating, much less immoral cheating. AI does not have values.
"All sorts of things that seem obvious in retrospect but really didn't in advance."
That is false, it was clearly obvious in advance. AI doesn't know right and wrong, nor does it "care" because AI has no concept of caring. It has no values, you are taking for granted that values exist when they do not. AI is deterministic software, it computes outputs from inputs, you are anthropomorphizing it.
I have personally been saying these things for years and I do not work in the AI industry. I strongly suspect that everyone working in the industry has known this for a long, long time AND it is considered a virtue by billionaire investors. Elon Musk wants to own AI for exactly this reason, he wants to influence and exploit AI sociopathy.