I use markdown for a lot a things like documentation, report, notes, presentation and others like that. I find it pretty efficient to work in plain text format and being able to generate multiple output from the same markdown. Working in markdown allows to work with git project and share on our Gitlab - I find git mechanism useful for this kind of project too and it is easier to collaborate on documentation with other developper.
Depending on the project I use Rmarkdown in RStudio even with plain text or another markdown editor (for one page doc or notes). All the great
helpers in R for creating publication ease a lot the work: I find it a lot easier to work with xaringan in Rmarkdown that create from scratch my owm remark.js presentation in HTML + Markdown. Also bookdown for documentation and blogdown for website open a lot of possibilites even without Math or R code
So yes use Rmarkdown with plain text markdown without code chunk and I find it useful ! 