I think it’s been mentioned a few times that they like to keep the chats moderated (which makes sense, because unmoderated anything related to video games tends rapidly towards shiftiness) but I think also because if friends want to chat, they can use any of a hundred other options (including just friending one another on Discord), and also also because I believe they’ve mentioned that if anything cool or interesting comes up, it’s useful to have a record that can be easily consulted.