The people in the ditch are the people who don't know how to drive in the snow. The slightest slip and they're on their brakes like white on rice. THAT sends them into the ditch. There may be a correlation between assholes who don't know how to drive & SUV ownership - that remains to be determined. I've driven plenty of times in foot plus deep snow, including off road; 4wd works just fine. I agree with your assessment of ice though...
4wd, awd, it doesn't matter. You're not driving on iced over roads. (Hence the reason I'm in here at this time - no school. Not a flake of snow or drop of rain at the moment, but a lot of areas in our school district were experiencing freezing rain.