http://wccftech.com/esrb-clarifies-stance-loot-boxes/

Are loot boxes a form of gambling? It’s a question some are asking as fan resentment over the way loot boxes are being added to games like Forza Motorsport 7, Middle-earth: Shadow of War, and Star Wars Battlefront II boils over. The charge is being led by popular YouTube personality John “Totalbiscuit” Bain, who has called for the ESRB to officially classify randomized loot systems as gambling.

This is significant because ESRB guidelines state any game with “real gambling” — that is, any wagering with real-life cash — is automatically rated AO (Adults Only). Most North American retailers, including Walmart and GameSpot, won’t carry AO games, meaning a lot of big games would essentially be banned from sale if the ESRB decided loot boxes constitute gambling.