Sure it (shorting against the box) can be used to defer/reduce taxes. That's one common use of it.
Say you have a stock that you'd like to sell, but you don't want to pay taxes this year. What you do is instead short it ("against the box" since you still keep your original shares), thereby locking in the current price. Since neither your long or short position is closed, you currently pay no taxes. Then, whever you want to take your profit (e.h. next tax year, or when you have offsetting losses), you cover your short position and sell your shares, thereby becoming liable for any taxes owed.
That the way to defer taxes...but you can also reduce taxes to ZERO by simply NEVER closing the positions.... You buy a stock (or get in in an IPO), then rather that sell it short againt the box, thereby getting your cash, and NEVER close either long/short position, thereby never incurring a tax liability. People actually do this - it's not just a theoretical tax hole.