Why are you horrified an disgusted?
I would say because women are being treated like slabs of meat, having their genitals cut without any warning or even being asked.
Tearing is almost ALWAYS less painful, quicker to heal, carries less risks, less infections etc so I know I would be livid if I was cut instead of being 'allowed' to tear naturally.
I have birthed 9lb babies with only a graze and a 7lb baby with a small tear so its impossible for an ob to predict you will tear and how badly imo.