But if they didn't even come close to measuring it then there would be no correlation ? It's not like these tests are applied retroactively to explain past performances - they offer actual predictive value. Selection bias can account for some of it but there are ways to test if this and from what I've seen it still holds up.

SAT scores would be positively correlated with success even if they were entirely random as long as universities continued to use them as a factor in admissions. It's sort of a corollary of Goodhart's law that it is difficult to assess the quality of a measure while it is being used as a target.

I’m not disputing that these tests measure something, they obviously do. However what they are measuring is not what most people consider a satisfactory definition of intelligence. In fact most psychometricians simply give up and define intelligence based on what these tests measure (i.e. operation definition). Without justification that is very poor science.