The most effective way to filter on raw IQ would be to... filter on raw IQ. But that's illegal.
It's not technically illegal, just legally perilous. Some companies do it, but they're companies that require a whole lot of other qualifications - "we only hire from Harvard and Yale" or "applicants must have ten years managing at least 150 employees".
The DoJ and activists are only interested in suing companies where a) it's difficult to rate individual performance and b) judges think that "anyone can do that job"