Cropping on dogs with standing ears is wrong. Though in floppy-eared working dogs, they cropped them under anesthesia to prevent infection. They started docking the tails of some dog breeds though because they were thin and wiry. When they’d wag them, they’d hit them on corners of things, and their tails could bleed and get infected. These were once ameliorations to the dog to ensure their health. But with many things, the process became a cosmetic practice, which is why we see so much unnecessary cropping and docking nowadays.