It's just convenience, it has persistent chat, file upload, voice and video calls and screen sharing and an overlay and who knows what else people use nowadays. The average user doesn't care about data retention and availability, the inevitable enshittification of discord or their privacy, I'm still pining for the ancient days of forums, ts3, xfire/msn and IRC, which makes me feel old enough to just dissolve into the lifestream, but what can you do.