Even if you're not explicitly "cheating", if your job is more primed around pattern recognition and the like, you might still perform better on an IQ test than someone who works driving trucks. This doesn't imply that the truck driver is inherently more stupid than the person who reads patterns all day.

Have you heard of the 'g factor'? [0]

About half of general intelligence is this correlation between all the different types. Modern IQ tests measure something like 15 types, and pattern recognition is one of them. It's the correlation between all the types that really matters.

It is strongly linked to career success, educational attainment, and many other things in life that are typically regarded as positive outcomes. Lower g-factors correlate strongly with poor outcomes.

Regardless of what we're measuring (and if it can be improved with various interventions) it is something we can measure, seems to be heritable, and is strongly correlated with positive outcomes.

The GP's phrasing was harsh, but he's not wrong for insisting that good and bad are not the same thing.

Below average intelligence is something that should be fixed, not celebrated, and it's not just some cute and quirky Sesame Street "We're all different, but the same" thing. It's a disorder, like Depression or Schizophrenia. It should be treated, and ideally eradicated. People who have it should not be stigmatized for it, but they SHOULD be treated and at least taught coping skills - as they would be with any other disability.

[0] https://en.wikipedia.org/wiki/G_factor_(psychometrics)