Everyone has a responsibility for their own safety. We should do what is reasonable to reduce harm and risk to others, but there is only so much that can be reasonable. If a person wears dark clothing, doesn’t use crosswalks, doesn’t check for cars etc at what point does their safety become their responsibility?
I can absolutely see magic not being able to correct genetic or congenital conditions. It can make sense for developmental delays aswell. But something like missing a limb from a traumatic injurie or blindness due to macular degeneration… There is no reason a mid level adventurer or powerfull character would not just use magic to heal or fix it.
Maybe an injurie by a powerful lich, or since kinda of cursed weapon that makes it impossible to fully heal with anything short of a wish spell…
Poor people on the other hand, should absolutely have debilitating injuries and disabilities that will never be fully fixed due to magic being expensive.