I think that sentence was somewhat hyperbolic. It doesn't mean that there is literally no information about how Facebook works, just that it's a bit secretive.

The rest of the article does go into many details about the behind the scenes of Facebook's algorithm. And shares a number of interesting details about how it works, and how decisions about it are made. So I would say the title isn't that bad.

The current article title is fair enough i guess: "Who Controls Your Facebook Feed"

(i guess they changed it themselves, as the URL shows this old title)

Presumably nobody outside Facebook knows that either though?

But the subtitle answers it fairly (IMO):

"A small team of engineers in Menlo Park. A panel of anonymous power users around the world. And, increasingly, you."

And they not claim they know themselves.