What's the deal with packing out human waste?

The idea of packing out your human waste can be fairly (to completely) unpalatable but there is no doubt that it leaves the least impact on the local environment of any other method of disposing of human waste. Packing waste out of sensitive, highly used areas is likely the only realistic option for minimizing the impact on the area. The Center encourages outdoor enthusiast to give some thought to the impact (human waste in particular) that they leave behind which will undoubtedly impact other people, water, wildlife or all of the above. Generally speaking, the Restop, Go Anywhere (formerly WAG Bag) and Biffy Bag systems are easiest for backpacking/hiking use, while the others (such as reusable, washable toilet systems) are better suited for paddling/rafting trips. The Center encourages outdoor enthusiast to consider the four objectives of proper disposal of human waste and to strive to meet these objectives:
• Avoid polluting water sources.
• Eliminate contact with insects and animals.
• Maximize decomposition.
• Minimize the chances of social impacts.
The Center also recognizes that there is a spectrum of options for properly disposing of human waste in the out of doors. Options include:
Toilet facilities -> Outhouses -> Privies -> Catholes (burying the toilet paper deeply in the hole) -> Catholes (packing out the toilet paper) -> Packing out your human waste.