It makes them feel more useful. http://i.imgur.com/B5Ms29e.gif?Noredirect
This happens to me a lot as a split pushing Nasus who is doing well. Like, do you not see my q's on the turret and the damage I do? I would rather if they ping me MIA or danger in the upper jungle path so i hide and recall in case i cannot take turret on time.
When people do this it makes me want to die. Over pinging is the woooooorst especial if the person doing the over pinging is a feeder....