You have to try hard to get negative karma in a sub
You can get -60 karma on conspiracy sub for saying that witches aren't real therefore John Podesta doesn't practice witchcraft.
Also having that negative karma feature on any political sub amounts to a total ban on all politically incorrect opinions. If most people on a political sub are for candidate A, you will never be allowed to share your support for candidate B. Making it wrongly seem like candidate B has 0% support and candidate A has 100% support.