Yes, the defender has to be within 1 step of hitting the QB in order to avoid the penalty. If you review the games, the defender is normally more than 1 step away at the time of the hand-off. In reality, in this scenario, the defender would always "take" the QB but only hit him if he keeps the ball or if the defender got there earlier than normal. The QB would always hand-off the ball and the RB could not cut outside in the direction of the QB defender; therefore, the offense would be more predictable. There is some benefit to the defender deciding in advance which player (RB or QB) that he is going to "take"; however, it is not as easy or simple as "always hit the QB".