VOLUNTARY blacklists are used to mitigate harassment and help filter out boring content (spam).
It's just like setting a spam filter on your email, if someone is harassing you, you just filter them.
It doesn't "do anything" (scarlet letter/black mark) to the "bad" person, unless you VOLUNTARILY join (subscribe to) a blacklist that happens to have that person on that list.
For example, if this proposal goes through, the first thing I'll do is UNSUBSCRIBE from marky's vigilante BS blacklist.
You might like this, @blocktrades/hive-improvement-proposal-decentralize-blacklists-on-hive
There's a proposal to make hive blacklists opt-in/opt-out.
Basically like a mute-list that any individual can create for themself and then others can choose to subscribe or unsubscribe to that user's mute-list (so they don't have to create/maintain their own mute list).
If this gets implemented, I might just abandon the old platform altogether!
Perhaps anarchy already exists and "THE COMMUNITY" is merely the highest manifestation of organized crime. – special thanks to 
+proHUMAN +proFAMILY
Your scathing critique is requested.