TP takes a long time to degrade, and just making sure you are off the trail isn’t enough to make sure it stays out of sight. Animals can dig up TP, especially if it is just covered by leaves rather than buried in a cathole, and erosion and other natural causes will bring TP to the surface as well. And coming across someone else’s used TP along the trail or off the trail in the “backcountry” is just GROSS!
Packing out used TP really doesn’t take much effort, and it isn’t gross either as long as you drop it in a ziplock bag as soon as you use it (instead of dropping it on the ground or in a cathole). And it is a lot faster than digging a cathole if all you are planning to bury in it is used TP.
Kanga