I don't personally think the Sequences count as Dark Arts, since I don't think EY was trying to employ them. At the same time, they were written by someone who very definitely assumed the social role of the wise and informed guru, who used humor, and all sorts of excellent rhetorical principles to make his points as persuasive as possible. If someone were to deliberately use those techniques in order to persuade someone of something because rational reasons wouldn't work, then I would call it Dark Arts.