I take Tufte as doing something slightly different than what his stated goal is. I see him more as playing with design principles to build visual grammars very different than we're used to, that sometimes run to extremes - like the Napoleon chart. The information density, compared to a normal chart, is huge and the conventions, well, unconventional. Also, it took a ton of labor, and there aren't really tools for normal humans to create such charts in the time people typically have for Powerpoint. So I see that chart, in particular, as a demonstration model, or maybe an art piece.