I actually would object that geographic data should rarely be shown on a map. A data visualization should be chosen such that it helps the viewer to better und

I actually would object that geographic data should rarely be shown on a map. A data visualization should be chosen such that it helps the viewer to better understand the information contained within. Maps are great at showing some very specific types of information, namely boundaries around areas and the positions of those bounded areas relative to one another. If you have information that is intimately related to those boundaries and areas, then by all means plot the information on a picture of those. The geographical regions in the article serve only as categories. There is no intent to educate or present the relative positions of those regions to one another. You criticize the extraneous green blobs. What benefit and clarity is gained by adding other blobs (shapes on a map) and divorcing the relative ranking from an easy-to-interpret linear scale? How does that aid in understanding the relative popularity of languages?