You’re actually one of the smart people I implicitly mention at the end of the article as working on the problem, and your 2014 work was definitely weighing on my mind when I wrote this piece. I think I even asked a question about whether “literacy” was the right word at VIS that year, and the answer I got was (accurately, I think) “maybe not, but it’s the best one that we’ve got so far, and there’s already a lot of momentum behind it.”
If “chart literacy” is a useful metaphor to get good things done, then by all means use the metaphor in a useful way. The concerns that I’ve highlighted here are more about the parts of “literacy” that creep over into “chart literacy” through this metaphor that may have no business being along for the ride. Specifically that’s things like “not showing complex data or charts to people because we assume that our audience wont get it” and the related “not providing pedagogical tools or supplemental text with our charts because we assume that our audience doesn’t need it.” It’s this relying on literacy as an excuse, or as a disabler rather than enabler that concerns me most.