Yeah, it's not a completely fringe idea that there are no moral facts. I might be wrong in my position that there are moral facts. What I'm not wrong about is the need for belief in moral facts.
When we reject belief in moral facts people won't condemn raping children. They'll try to distance themselves from child rape apology by saying that they'll kick those people's asses and take away their liberty; but, if there's no objectivity in morality, how to you justify your own violent actions against the child rapist? If the child rapist entirely believed that his actions were morally just and you don't believe in objective moral values, how do you justify acts of violence against the rapist? How do you argue that acts violence against you aren't justified?
This isn't just random people on social media. An appointee of the Obama administration who was supposedly an ethicist said that we couldn't say that it would be morally wrong for a culture to remove the eyeballs of every third child if it were what they believed.
I find Sam Harris's arguments in The Moral Landscape to be flawed; but, we need to believe in moral truth. Otherwise, we can't condemn evil nor condone retaliation.