How does this compare to R Bookdown ( https://bookdown.org/yihui/bookdown/ ), which can do the regular markdown stuff, plus LaTeX, and also run the R code and embed results (tables, plots, etc.) into the book?
If you want to compare restructured text with R markdown, then they are simply different tools for different problems. If you want to embed code/figures/tables directly in the writing, R markdown is difficult to beat. Personally I would tend to prefer writing in either latex or markdown, but my reason is similar to the author's: I know latex and (R) markdown much better than I know restructured text.