> the benefits rise with IQ level - nothing new here, that’s the very definition of IQ

This is not obvious to me, and certainly is not the "definition" of IQ. There are tools that become less useful the more intelligent you are, such as multiplication tables. IQ is defined by a set of standardized tests that attempt to quantify human intelligence, and has some correlations with social, educational and professional performance, but it's not clear why it would help with use of AI tools.