Have you seen what happens when all the snow and ice flies off in one big sheet at 60 mph on the freeway? It can do some damage to others cars.
How about seeing through the windows? I have seen idiots with a small cleared spot on the windshield only and cannot see anything.
If people are not being responsible by clearing the debris off their cars, they should get a ticket. It is the only responsible thing as a driver.
I am sure everyone on here would chase someone down if stuff from their car did damage to their rig.