On Xbox Series X, I like to play Spotify while playing mindless games like D4. I can provide a long list of games which will stay open when I launch Spotify or another app after I open the game, then go back to the game. Diablo 4 closes completely every time. I know it’s not a multiplayer or network connection issue, because Halo Infinite or Master Chief Collection or Gears 5 can maintain the connection in the middle of a match. The same is true on PS5. It’s possible to launch an app and return to the game.
So this is me formally requesting this feature for versions on Series X/S (with current parity on PS5). Good news, it doesn’t even require balance changes to the game itself and it uncontroversial. Easy win.