I use RStudio with `knitr` when it is the wrong tool, because it is just too easy to make something that is easy to read and people think I put a lot of effort into formatting. I do have a few templates that I use so that the text isn't always Computer Modern, but it is mostly a mix of Markdown, Latex math, and features from R like `kable` for making tables. I even tend to plot graphics into the text using R, rather than looking up how to place them using markdown.