Most people who have made a website with CSS before would at best change the font size, the line spacing and the font face and tweak it to a point that feels easily readable and call it a day. Introducing variable widths between the characters of the font, digraphs and so on feels like more like exercising artisanship that only the experts would see value in rather than solving a technical problem.
Perhaps advanced web design/typesetting is the main application of this and it has a chance of inducing a better subconscious effect on the viewer. Sort of how magazines and books were designed back in the day I suppose.