I find it amusing that people think snowboarders ruin bump runs. I actually don’t see that many snowboarders on moguls, it’s usually not their favorite thing. I see a lot skiers ruining bumps, and then again, it just makes the bumps a more interesting challenge. I don’t need them to be perfectly symmetrical.
For some people (say, my SO) the biggest complaint about snowboards (more so that the snowboarders) is the loud scraping sound they make, which freaks her out when it’s coming from above her and she’s concerned she’s going to get hit, which has happened. That said, most boarders are just like skiers, nice people, happy to have a good time without terrorizing anyone.
I do see many boarders trying to ride steeper terrain much sooner in their learning curve than skiers, and that’s where you see a lot of the side slipping and scraping of snow. I think skiers side slipping on the same terrain would do the same thing to the snow. I think it’s simply a matter of boarders being more likely to over-terrain themselves, for whatever reason. I don’t know what the ration of boarder to skiers is/are, but I do know we have far fewer snowboarders than skiers taking lessons at my ski school, and I think it’s also the case for the other ski schools in my area. Given there is a lot of advanced terrain in most of the PNW ski areas, it results in snowboarders taking on terrain without the skills to really ride it.