The simplest, most traditional definition of "literacy" is "being able to read and write." There are much more sophisticated conceptions, but if I say "the literacy rate of Grand Fenwick is 23%" you don't think "I'm surprised only 23% can storyboard, shoot and edit a short video." Or "Gee, I didn't realize the Grand Fenwickians couldn't solve problems in groups." You think "Only 23% can read and write?"
Similarly, the traditional minimal role of schools is to teach literacy, to read and write.
When we try to define new "literacies," what we're really saying is "this is something that I believe must be taught in school." That is, if I convince you something is a "literacy," I've convinced you that it must be taught.