as grumpy mentioned i could see how maybe they would be useful racing cross with how much things get banged around. a properly adjusted rd will put the chain in the spokes with a slightly bent rd hanger...and going down in the mud is not that uncommon.

plus, with cross racing the bike is usually covered in mud and grime, who cares how it looks or about a few extra grams.

for the road, yea, they're pretty disposable.