Case 1:
you select an event, playhead follows selection and moves to event's start position
you press play, then stop. now playhead has moved a little. event is still selected
if you select an event again, playhead won't move to event's start position, because event can't be reselected
Case 2:
you select a range on event, you make a mistake and want to reselect a range.
you won't be able to do it, because this action will cut the range and move it.
instead you have to manually correct the existing selection.
reselection will be faster.