Unconscious bias is really really hard to get past in job interviews. People have this weird instinct where they want to work with the kinds of people that they've worked with in the past. A well implemented DEI program nudges the scales towards selection of candidates who are best for the role, rather than who are most similar to the interviewers. Implementing an effective DEI program is hard.

The other side of that is also true. Candidates want to work for teams that include the kinds of people that they have worked with in the past. Because of this, having visible diversity in your teams is more likely to attract a wider candidate pool, which means more chances to hire good people.