Can you remember a time when it was suggested (by your parents or some other adult) that you don't do something, and you did it anyway? For example, that you don't ride your bike near the charcoal grill? And you foolishly ride your bike not only near the charcoal grill, but right into it?
Can you picture the look on your Dad's face, if when he asked "why did you ride your bike near the charcoal grill, after I told you not to?" you replied "what difference does it make?" Not that this happened to me mind you (rubbing her sore behind). It's just an illustration.
What would happen if you or your team at work made a miscalculation, or a flat out boneheaded mistake, or were not on top of something that you should have been so a deadline got missed. And when you were questioned on it by your boss, if you replied "what difference does it make?" how many more opportunities do you think you'd have?
Picture key officials in the White House or Congressional leaders, trying to figure out what to say about some key decision they've made or on the verge of making, and picture someone asking a probing question, a question like "why did you..?" or "why didn't you...?" and then in your head, imagine what it would sound like if they said "what difference does it make?"
In case you can't imagine that, you don't have to. Here are a couple of actual examples.
Watch Hillary Clinton ask "What difference does it make?" when discussing Benghazi.
Watch Harry Reid ask "What difference does it make?" when discussing the Bowe Bergdahl prisoner swap.Ask yourself 'What difference does it make?'