It does not change the default quiet mode settings. Instead, you are offered an option in the file menu to open a scene without popups. Any popups. Including missing assets and others that might tell you that something's wrong with a scene, for example missing plugins. That's why I'd not activate it generally.
Opening a scene with the menu item turns on quiet mode, loads a scene and then switches it off again. This is perfect for "known scenes" you work on and to avoid clicking away xref objects scaling confirmations and similar "yes-I-know"s.
Good Luck