I think that you're missing my point. Those "non cognitive" skills tend to be correlated with high cognitive ability. But they aren't exclusive to it.
Frankly it depends on your definition of success. In an extreme example, we had a young man with Down's syndrome who cleaned our office and did some maintenance a few years ago. He demonstrated all of those non-cognitive characteristics, lived independently and seemed to be happy. I would argue that despite a fundamental deficit in cognitive ability and a corresponding low IQ, he was a successful adult.
In the context of a conversation about Japan, where success is getting into a school and becoming a salaryman, those non-cognitive skills (which were broader than just the much-hyped "grit") are meaningful once you hit some average threshold of brainpower.
Salarymen make up a small portion of the Japanese workforce... much smaller than blue collar workers, part-time workers etc. This may be seen as THE path to success by some, but not everyone, especially in rural areas and among younger cohorts.
Frankly it depends on your definition of success. In an extreme example, we had a young man with Down's syndrome who cleaned our office and did some maintenance a few years ago. He demonstrated all of those non-cognitive characteristics, lived independently and seemed to be happy. I would argue that despite a fundamental deficit in cognitive ability and a corresponding low IQ, he was a successful adult.
In the context of a conversation about Japan, where success is getting into a school and becoming a salaryman, those non-cognitive skills (which were broader than just the much-hyped "grit") are meaningful once you hit some average threshold of brainpower.