Back agin and witha crack theory to boot - Genshin Impact (Basic Mode) - Sumeru (3)

Paraphrased answer from my friend, with my own conclusions added: People are generally afraid of what they don't know and doctors are "people with mysterious knowledge", so people throughout history were generally afraid of what they could do with said knowledge, which is why people who knew too much were branded heretics and painted as a danger to be avoided or outright executed. This, as many things, bled into fiction and became a staple character archetype.