On the contrary. A part of the essay is available online, from the linked page. Tufte is very clear that it is possible to have informative presentations - but slideware does not help towards this goal. He argues that slides have a terrible bandwidth, and do not help anyone but the worst 5% of presenters, where they help by imposing structure - any structure at all - on the presentation. All other presenters, he states, would be better off without slides, and should rather just talk, or, better, give their audience their ideas in written form, as sentences made of words rather than slides made of points, and talk about them once they have been read and understood.