Even with regular maintenance, gutters can be damaged in extreme weather, wind storms that bring down tree branches onto a gutter, trucks backing into the gutter system, etc. In some cases the gutter system can be repaired or it could present an opportunity to upgrade the entire system if it’s near the end of its useful life.
Gutter erosion is also a common issue for gutters that were not properly installed or regularly maintained. This could accelerate the lifecycle of a gutter system and thus require replacement.