I think the tree huggin eco nazi's blame all forms of soil and eco system erosion on the backpackers and hikers. The hikers blame it on the horse back riders, the horse riders blame it on the dirt bikes, the dirt bike blame it on the quads, the quads blame it on the Jeeps, the Jeeps blame it on the full size four wheel drive trucks and the full size trucks blame it on the loggers.
It's human nature to blame it on others. It's not possible to dictate common sense, so you cannot pass any laws to protect the trails, that are enforceable. It really is a shame when a nice trail or riding area gets torn up. The only thing I have found that actually works is, leading by example. And since most of us ride trails in groups, we can educate, one on one, the members of our riding groups. The guys I ride with will pick up litter and trash when they stop for a break, that has taught me to do the same. The example each of us sets, is watched by all others.
John