During the Great DC Area Snow Nightmare it did indeed take me 6 and a half hours to get home. I felt better about it once I heard some folks took as much as 13 hours to get home!
For what I was able to observe myself, the problem was 100% the people who were out there who had no business trying to drive in the snow. The conditions weren't that bad! It was snow, not freezing rain, in fact it was above freezing the whole time. Snow has sort of a grainy consistency, so in some ways it is like driving in sand. Once cars have driven on the snow, it packs down into an somewhat of an ice-like quality, but it is not ice, it still has a certain graininess. Yet even before there was much accumulation, cars ahead were stopping traffic because their tires would only spin on that. These people simply had cars or tires that were unequal to this mild challenge. This would usually be on a slight grade, but sometimes on no grade at all! Desperate to keep going, they would wind up in the middle of the road stopping traffic. I did not see one accident. Outside of sheer congestion, of course, there just seemed to be this one problem!
To tell you the truth, I didn't know you could even buy tires today that are so useless in the snow that even front-wheel drive vehicles would get stuck like that.
One can only hope these drivers now know and will all stay home next time.