There’s also the issue where, if you’ll cede for the sake of argument that general intelligence exists, that does not mean that being very educated in one thing gives you an education in other things, and there are principles of reasoning (and proofs and such) that are present and frequently used in some fields but not others, so general intelligence doesn’t get you very far when you are deeply uninformed because even basic reasoning within a field may be beyond you in many cases (unless you actually study it like the people in that field did).