In theory they try to get people hired for their competence rather than their network. A widely-cited anecdotal example of this reportedly working well is the Rooney Rule: https://www.espn.com/nfl/playoffs06/news/story?id=2750645

This thread also has a lot of anecdotal examples of failure modes of 'diverse slate' rules, though, such as people who have already decided who to hire still interviewing women candidates just to appease the rule, thus wasting everyone's time.