My son is/was in the same mind set as you until we did a test in 9" of fresh snow on the road with an ice bottom...His Chevy 2500 HD with Toyo tires(factory syped). against my 2WD dually,both empty with no weight in the back...My tires are syped AT3's....My 2WD dual tires stayed on the road without sliding and never broke traction at all while his broke traction more than once and slid in one corner...
With his in 4X4 he never broke traction or in any corners either..My wife's FWD dodge also broke traction once but did better than the 4X4 in 2WD..The dually did as well as the 4X4 in 4X4 in the city driving normally....
I can agree to disagree on this from my personal experience with a2WD dually and a 4X4....I truly think tire width on a dually is the deal breaker for good or bad traction...a put a set of doubles with Ice cleets and some weight in the back and it's a snow going monster...LOL