I don't get the point of "skin-out" weight.

It is mostly useful for capturing the weight of items in your pockets, your trekking poles (if any) and your footwear. Plus it smoothes out any differences caused by what you are wearing at any particular time. For example, if I zip off my convertible pant-legs and stick them in my pack, my pack weight goes up a few ounces, but my skin-out weight remains constant.

It also makes for a less fraudulent point of comparison with other hikers, if you are caught in a cut-throat game of "who has the lightest set-up?"