Until you work on machinery built in Europe. Those guy love NPN sensors to sourcing inputs and sinking outputs. And I agree that if the wire gets grounded out it's bad because things then turn on that shouldn't be on, and the PLC thinks are off.
They say it's because NPN devices respond faster, but when I asked Why that mattered when the PLC was only scanning the input at a much slower rate and that difference would only make an input read high one scan earlier once out of every 1,000 times it goes high, they couldn't provide a valid answer. Plus they were just regular inputs, not FAST-DC or HSCE.