I agree, the hunting instinct depends on the cat's temperament not the degree of 'wildness'.
We have 4 cats, they all sleep in the house and we feed them plenty. The oldest cat is lazy and doesn't hunt (she is actually an ex-feral who now seems to enjoy her old age in comfort), but the 3 younger cats are out hunting for hours every day, in all weathers. We don't have rats, but we get an endless stream of daily 'presents' from mice & voles to rabbits & squirrels, and even moles sometimes.