That’s an example of a component for a step generator for a stepper motor. You’d set velocity or position and stop caring about generating steps (let the hardware deal with that), or use PWM, or getting a velocity/position from encoder for that matter.
- re-use of a configuration (read control system) on different hardware
- use components (filters, PID etc) to configure your realtime control behaviour
- defined interaction between realtime and non realtime