[DoctorOW]

There's a lot of analysis on this that is really easy to Google, so this is just the gist. Essentially, intelligence is an abstract and subjective quality. IQ correlates with what the big names in academia agreed were "smart people", back when such institutions were largely racially segregated. In particular a numeric/"empirical" standard was pushed for to give more credibility to eugenics.

[krona]

IQ also correlates with many other other things such as reaction time and other real, measurable phenomena, so to say 'yeah but that's just like, your opinion' is nonsense.

[DoctorOW]

All things being equal IQ could have some value however, bearing in mind I'm simplifying here, not all things are equal. IQ is designed to quantify intelligence, not reaction time. Don't just go by the comments here, even mine. Look into the history of IQ tests, for what purpose they were designed, and what they really test for.