Why do I need staggered (graduated) post tuners?

On a 6 inline Fender style headstock (Strat/Tele, and some others) that is in line with the fretboard (i.e. doesn't tilt back) you use graduated post tuners. There's a really good explanation of this on a Youtube video done by Josh Borisoff of Hipshot here: http://youtu.be/YijSKBGSZ64

Another side effect is that when you use staggered tuners, you don't need string trees any more!