I think Facebook has tried to block them but they pop up all over the place. The latest one seems to be PetFlow, which is ostensibly some sort of pet site but it's churning out clickbait like mad.
In short, I don't think FB has been particularly effective, though I admire(d) the goal.
After the rise of these viral linkbait sites, Petflow started emulating the model to keep up. I'm sure this has helped them continue to grow and keep up with these rising competitors like Buzzfeed and Viral Nova, but I personally feel like it's hurting their brand.
So Alex and Joe (founders of Petflow), if you're listening, stop the bullshit and go back what you were doing. These viral linkbait sites are a fad and will eventually go away or get banned. I don't want you guys to go down the same road.
In short, I don't think FB has been particularly effective, though I admire(d) the goal.