It's coached in junior football and is a strategy employed by most outside backs in the competition. The actual motivation is not to make a line break, rather it is the runner looking for the space between two defenders. When you run straight and hard, you're easy pickings to (a) get smashed and (b) lose the contact, resulting a slower play-the-ball. If you 'prop' and wedge between defenders, you can find your front, win momentum and get a quick play-the-ball. Most middle forwards are a different matter and they can use their size to win contact. That's something substantially harder for many outside backs.
That's the theory of it. As Clint Eastwood suggests, it's often to varying degrees of success.