Before epilepsy was understood to be a neurological condition, people believed it was caused by the moon, or by phlegm in the brain. They condemned seizures as evidence of witchcraft or demonic possession, and killed or castrated sufferers to prevent them from passing tainted blood to a new generation.
Sorry, I didn’t mean to ask as why the question of free will was discussed, but rather why the concept of free will is the default over the obvious. I moved around some sentences before posting and didn’t reword that appropriately. Thank you for pointing it out!!