Fallen Limbs
Pruning a tree does a few things. It redirects and refocuses a tree's resources and removes material which would block sunlight, invigorating the undergrowth.
It's also destructive and painful. Trees do this to themselves only to survive, discarding material that poses a sufficient risk. When we prune a tree, it's for optimization, not survival. Maybe it's easy to prune a tree because we so clearly see the rewards without feeling the pain.
Maybe there's no way to avoid the pain that's required to redirect growth.