Notice what I am objecting to is not the style advice in Elements, which might best be described the way The Hitchhiker's Guide to the Galaxy describes Earth: mostly harmless. Some of the recommendations are vapid, like "Be clear" (how could one disagree?). Some are tautologous, like "Do not explain too much." (Explaining too much means explaining more than you should, so of course you shouldn't.) Many are useless, like "Omit needless words." (The students who know which words are needless don't need the instruction.) Even so, it doesn't hurt to lay such well-meant maxims before novice writers.