Confidence and batting deep. Top and middle order can afford to throw the bat as they trust there will be someone else to take up the reins if they fail. I'm not knocking it by any means because it is fun to watch and has given results. On it's day, it's majestic.
There's no magic art to it either, the tactic is plain to see. It simply biases the game approach towards batting and out scoring the opposition. However, if you have a bowler, such as Starc, who can disrupt that game plan then it makes the tactic less certain to succeed. That's when you need your backup plan.