Your gutters are responsible for water management.
During a storm, they effectively channel water flow from your roof, through downspouts, and direct it to appropriate areas outside the home.
Without a gutter system, your roof can pick up a bunch of leaves and other debris, causing water to stagnate and overflow.
This can make your home vulnerable to rotting, rusting, and other damage.
In addition, gutters prevent water from settling around your basement.
When water overflows from your roof, it can seep into your foundation and slowly weaken everything that supports your structure.