I would also suppose that pulverizing the leaf would ruin one of the
great aspects of puer, which is that you can brew the same leaves over
and over and get a whole bunch of different cups of tea with just a
few grams of leaf. You can do the same with oolong, but puer tends to
have more staying power in my experience. With tea dust, as you find
in tea bags or finely chopped leaves even, I think the flavors would
leach out much more quickly and you wouldn't get nearly as much
enjoyment or value out of the tea.

cha bing