I've contemplated about the cv boots and how they would get torn. Only thing I could come up with is the constant pressure something would have on the surface as it spins. Think of it like a lathe machine. With a little point, you can shave off an edge on something that is spinning rather quickly.
So with an icicle from the melted packed snow, it could in all reality, cut the surface of the boot. I really don't know, just a thought.
I'm thinking those little guards the Dakar racers and desert racers use would seem to help in a condition like that. However, it could also hold from the backside the debri when you go backwards.