This timeline option was added in version 23.11 and is off by default. This option tries to automatically add an empty audio or video track to have ready so you do not need need to add them manually. An empty track also helps to provide some space in order to select by dragging a box or rectangle.
It only adds tracks when you add something to the timeline or move a clip between tracks. Also, it does not automatically add a track when you open a project with no empty tracks.