You're right in that there's no reason to believe AI can do this effectively.
However, in my experience, HR departments and hiring processes are anything but rational. HRs buy any kind of snake oil by the barrel, and hiring managers generally reach their position for reasons entirely unrelated to the ability to identify and hire above average employees.
HR departments are by definition on the defensive, that is a large part of what "human resources" is - a legal shield department to make sure employees stay in their lanes, with employment and legal threats as guardrails. All they need is a few pop culture articles saying these "truth/personality/job filtering AIs" are liability traps, and they will cease to be popular instantly. HR is a fear driven department, play on that.
However, in my experience, HR departments and hiring processes are anything but rational. HRs buy any kind of snake oil by the barrel, and hiring managers generally reach their position for reasons entirely unrelated to the ability to identify and hire above average employees.