From Road.cc:
You can use them [Dura-Ace shifters] to shift up through multiple gears, so panicky monster-hill-round-a-blind-bend downshifts are easily accommodated.
I'm sure when I started cycling, shifting up meant to a smaller cog, which was called a higher gear. Nowadays, some people call that shifting down, which is logical because the chain physically moves down to a smaller cog, and you can also mathematically justify calling that a lower ratio. But it's confusing when you don't know which way someone means by "shifting down (or up)". Using both in one sentence is just silly!