Gutters are important because that small, humble looking gutter on your house, is extremely important for keeping your home protected from rainwater. When it rains gravity pulls water off of the roof of your home. That water takes the path of least resistance on it’s way back down to the ground.
So, what happens if that path of least resistance leads that water into your attic? Or, what if it leads it to form pools at the base of your home that will eventually end up seeping into your home’s foundation? In either case, nothing good is going to happen.
Rainwater doesn’t care where it ends up, but you really do need to care about where it ends up.