DShot minimum throttle output


I have noticed that using dshot esc the motor is spinning even when the throttle input is zero.
In QGroundControl at the MAVLINK Inspector servo3_raw parameter was always at least 1, even without throttle command. In the code I have found in src/modules/drivers/dshot/dshot.cpp that when setting minimal inputs, it is set as DISARMED_VALUE + 1 . What is the reason of the +1 (e.g. avoiding division by zero)?

The links to the lines where it is added: