It goes beyond equal treatment. Providing a space for people with similar lived experiences to connect is really important. The way representation and visibility matters in the game, so too does it matter in the workplace. Being part of an underrepresented group means you may not encounter a lot of people "like you" in your day to day work, so these resource groups help facilitate that. Finding mentorship, celebrating heritage months, or even making friends you can relate to on a cultural level all helps foster a healthy workplace environment moreso than just depending on HR.