When we make an opening lead, it becomes a race as to who gets their tricks first! If we become lazy and not listen to the bidding, we will not be able to defeat contracts, and lose the excitement of the game.
When we have very few points, it is best to lead from what we have, and try to lead your shortest suit, in anticipation that we lead partners longest suit.
Conversely, when you hold all the points and expect partner to have none, we lead passively (from what we do not have), so as to give no extra tricks away to the declarer.