That’s a fairly new feature since the late teens. On older boats, with a switch, the bow switch controlled the accessories powered at the bow, such as the trim switches and Nav lights. This prevented inadvertent switch on of those items by stepping on switches.
On later production the addition of Live Scope (FFS), these last three years, the switch is used for forward facing sonar power. Not everyone wants that on premanently, thus you can switch it off. Some people believe FFS is felt by large fish, or schooling fish, and they move. This allows you to turn off FFS units.