I won't object to the "defragment" term, because in a way meditation is about alignment, and so is hard drive defragmentation. It puts like energy, data and entities to other like energy, data and entities, to achieve focus, locality and so on.

But I wish we delved more into why and how would this happen by "focusing on our breathing". I suppose being awake and doing nothing does give the mind a chance to run some "background optimization". But how is this different than when we're idle while we sleep (we only spend dreaming a small fraction of the time we're asleep).

The easiest way to think of Vipassana is as a method to defragment your mind.

Just like when you use the Windows utility to speed up your computer when things start slowing down, Vipassana does the same for your body and mind.