> Another interesting question is why the frontier labs are piling on pure maths

The reason is that the original scaling axes (parameters, training tokens, test-time compute) have saturated already, but RLVR (reinforcement learning from verifiable rewards) is still scaling well. And math has this nice property where you can synthetically generate arbitrary volumes of rewards to train the model, because math is self-contained and completely objective. Open-ended reasoning and analysis don't have that convenient property, and that is why progress is much slower outside of math and coding.