You're thinking the common view of affirmative action. DEI isn't just about hiring. It's about educating your workforce about different people's backgrounds & lived experiences. If you hire someone who is ideal for the job with years of experience and an absolute win for the company, then some other schmuck cracks a deeply offensive joke based on their race, sexuality, age, disability, etc., you have essentially created friction within the team at best, but also the possibility of that hire leaving for a more inclusive company.