That joke doesn't support the claim that police aren't a force for good, only that they have been a force for less good for blacks. Of course no one is better off by "abolishing the police" (unless you're a fan of a global dark age).
this argument always comes up and its complete and utter bullshit. Please think about what you say for more than a half second before you say it.
Police are not that effective, society does not completely collapse in their absence, and there needs to be a cost-benefit analysis done for even things that obviously seem good. When police murder and assault people regularly, using military equipment, that's a serious cost to take into consideration.
Overpolicing has serious consequences, and the evidence suggests it actually increases crime. When NYC cops stopped proactive policing, _serious crime decreased_.