Many higher current switch designs rely on the separation arc to assist in dispersing contact corrosion.
2.
To combat contact corrosion, a switch is usually designed to have a " wipe " action so that the contacts are cleaned.
3.
A switch designed for high current / high voltage use may become unreliable if operated at very low currents and low voltages, because the contact corrosion builds up excessively without an arc to disperse it.