If you don't see anyone mentioning what you wrote that's not surprising at all, because you totally misunderstood the paper. The models didn't suddenly drop to 5% accuracy on math olympiad questions. Instead this paper came up with a human evaluation that looks at the whole reasoning process (instead of just the final answer) and their finding is that the "thoughts" of reasoning models are not sufficiently human understandable or rigorous (at least for expert mathematicians). This is something that was already well known, because "reasoning" is essentially CoT prompting baked into normal responses. But the empirics also tell us it greatly helps for final outputs nonetheless.
On top of that, what the model prints out in the CoT window is not necessarily what the model is actually thinking. Anthropic just showed this in their paper from last week where they got models to cheat at a question by "accidentally" slipping them the answer, and the CoT had no mention of answer being slipped to them.
If you don't see anyone mentioning what you wrote that's not surprising at all, because you totally misunderstood the paper. The models didn't suddenly drop to 5% accuracy on math olympiad questions. Instead this paper came up with a human evaluation that looks at the whole reasoning process (instead of just the final answer) and their finding is that the "thoughts" of reasoning models are not sufficiently human understandable or rigorous (at least for expert mathematicians). This is something that was already well known, because "reasoning" is essentially CoT prompting baked into normal responses. But the empirics also tell us it greatly helps for final outputs nonetheless.