Of course 'fake news' (or BS as I like to call it) will outperform fact checkers. Most people want their view confirmed, and will buy the wildest claims before they accept, "Hey, maybe I'm wrong, and maybe this other guy ISN'T Satan in the Flesh." 

After all when one side is buying that the other side's leader runs satanic child sex rings out of the basement of a pizza joint? The other side believes that the first side is going to make it illegal for welfare recipients to have more than $20 in cash on them? And both deny to their last breath that they're wrong and maybe the other side isn't as evil as they think it is? 

Fact checking sites just can't compete with that fervent jingoism for their truths.