One Chip Many Programs
Using as DIP switch like below is common/traditional way to active/deactivate different programs or features on your program. Flipping one of these switches ON or OFF can give Power or Ground to a PIN of a microchip. If you use the Boolean Logic on the Arduino, you can then “active/deactivate different programs or features” in your greater program. DIP switches like these are usually not “user facing”, they are typically for an engineer or technican to use, like in a TV cable box to turn on/off premium channels, for example. But sometimes these switches are user facing in a number of off-the-shelf thermostats for example.
When you put “jumper wires” in your last project, they were to emulate this types of circuit switches. You find them useful as your projects get more complex and may have different types of users that your one device needs to work for.