> model capabilities across the board have only meaningfully improved in places where the labs are focusing their training efforts

That doesn't seem right. I use these models as research assistants when writing lots of random blog posts (including in economically ~useless areas like the history of contra dance) and Fable 5 is a serious improvement (when I don't get downgraded!) over Opus 4.6-4.8 which was a serious improvement over Opus 4.