Video games can be cruel sometimes. After all, The Computer Is a Cheating Bastard. However, some games feel sorry for a player who might need a positive shove. When done well, this creates a motive for less experienced players to keep playing and a deeper layer of strategy for more experienced players. When done shoddily, it will needlessly drag out a match longer than it should. In general though, the purpose of such mechanics is to keep the game close so that less experienced players aren't left in the dust, which can have disastrous results in the game's popularity.