There isn't an idea that "IQ is some innate fixed quality". There are two separate actual ideas being conflated there: that intelligence is an innate fixed quality (which is more or less definitional), and that IQ accurately measures intelligence (it doesn't, and we already knew that, but it's the best we have).
> There isn't an idea that "IQ is some innate fixed quality"
Actually yes there is; I have come across many people who believe this, specifically saying that IQ is fixed.
> that intelligence is an innate fixed quality
I would also disagree with this — intelligence can be increased, (e.g. through education, training, and practice), and also decreased, (e.g. by lifestyle / environment).
