This. Road condition is the key. Most of the water you collect while riding, even with full length fenders, is dirty water sprayed by your and other users tires. The rain itself usually account for very little in comparison.
The article mentions "mountain bikes" several times, which implies the failing bikes aren't ridden on roads at all. The fenders shown on the picture are not the same ones to be used on the road. It's possible we're talking about two completely different types of cycling.
