If it captures such a small facet of what it means to be human then its a very poor metric to optimize for. We don’t even know what trade offs we are making.

The statement "You might argue about the fine-grained distinction between the smart ones, but you wouldn't find somebody who you considered smart who somehow still had a 50 IQ." seems to claim that IQ models human creativity- or rather, human intelligence ("smartness")- comprehensively.