The things you list are all to do with winding up with differences as adults. The item brought up in the article has to do with girls becoming adults earlier. Which is separate, but also important, since it is one of the facts that helps girls get into college at higher rates than boys. (A trend whose long-term impact is not yet felt.)

And earlier maturation is not simply cultural, because it is tied to the very physical maturation of hitting puberty. Which is a biological process, not a cultural one.