Not specific to Moab, but anytime I have ever been confronted by someone saying I was hurting the land, be that by offroading, hunting, or even hiking, I always make the argument that the fastest way to damage a piece of property is to get people to stop caring about it. When you stop allowing people to responsibly use it like this, no one will have any incentive to protect it. Lots of Jeep clubs do a ton for the land. I'd be curious to know how many tons of garbage they haul out out of natural areas around the country each year.