moderation will never stamp out but the tiniest of hate/ignorance that will come. the only thing that will work is removing the one thing the trolls feed on... your reaction.
Hate and abuse are definitely hard or impossible to eradicate completely but we can do a lot better than current social media platforms and places like the Steam forums are doing.
By shining a light on these groups you attract others to it. This is why (I personally feel) the extreme right and extreme left exist today in politics. When you highlight (even to shame) a group it galvanizes them and brings other loonies to their cause.