The terminology and practice comes from the time when drones were primarily built by hobbyists. Rotors are dangerous for fleshy things, and it's easy to leave c

The terminology and practice comes from the time when drones were primarily built by hobbyists. Rotors are dangerous for fleshy things, and it's easy to leave controls in an unsafe state (throttles especially, they usually don't have a spring return). An arming sequence prevents accidents when tinkering and requires the controls to be reset. Like if you're connecting a battery preflight, you don't want the rotors to suddenly spin up and slice your arms to bits. Exposed CF blades spinning at 5k RPM can really mess you up.