I get why a single number is convenient but it also seems like it has to be losing something important. Two people can have the same IQ of 115 but one might be exceptionally strong in verbal reasoning and weak in processing speed while the other is the opposite. Those seem like meaningfully different cognitive profiles that a single number completely hides. So is the g score actually the most useful thing to report or are we losing critical information by collapsing everything into one number?
This is one of the more legitimate criticisms of how IQ gets communicated, even if it is not a criticism of the underlying science. G is real and it is the single strongest predictor of most outcomes, so collapsing to one number is not arbitrary. But you are right that it hides meaningful profile variation. Two people with identical full scale scores can have very different cognitive architectures and those differences matter for predicting specific performance domains, diagnosing learning differences, and designing interventions. The CHC model exists precisely because researchers recognized that broad abilities like fluid reasoning, crystallized knowledge, and processing speed are meaningfully distinct even though they correlate. That is why multidimensional assessments that report scores across multiple indices give you more actionable information than a single composite. RIOT IQ does exactly this across 6 cognitive domains, which means you get the g estimate but also the profile underneath it.
G is the most important single number in psychometrics but it was never meant to be the only number. The researchers who developed the concept knew the full picture was more complex. The problem is not the science, it is how the science gets simplified when it leaves the lab.