Most snowboarders are beyond useless, but the real speedbumps are the things they leave behind after sliding straight down the entire hill. Sheer ice followed by big irregular moguls, thanks snowboarders.
I went riding last night with my son, who skis. Funny watching all the /\'ers going straight down the slope.
You get that from both camps. Newbies are just learning the physics of the gear, so have some patience. I just picked up snowboarding this year and am about out of the beginner phase. But on my first day or two, you can bet I was just toe/heel sliding down, leafing, and doing garlands so I could get a feel for things. No different than a skier /\'ing straight down, which I see every day I'm out there.
I've gone skiing quite a bit over the years, and I don't recall ever seeing 'sliders' traversing anything other than the green circles. So if you're encountering snowboarders sliding straight down the entire hill (or skiers who are just /\'ing the whole way down), maybe you're on the wrong hill?