you should see what the heavy rain does to some trails 8O i've even seen sediment and rocks that started at the top of a hill end up halfway down!!!! rain causes much more damage than the odd locked back brake from what i've seen.
i've been out there with lots of scientific measuring stuff and i can safely conclude that the weather damages stuff, as do people walking, people riding, people skidding, animals mating whilst wearing studded bondage gear and so on….