>D&I may very well be operating at the wrong end of the pipe.
Then that should be the argument at hand. Not rejecting the idea outright.
>she was pressured into hiring an incompetent person
That there is no system in place for addressing concrete performance issues in any employee is the failing of the organization. The requirements for any role you hire for should be clear, expectations should be set and when they are not met there should be consequences. If this is not the case at the organization she worked at, she was bound to burn out, irrespective of the DEI objectives.