Unless you're doing in-depth statistical analysis, there's not really any reason to know anything about R. It isn't a useful general purpose language.

That is to say, while your suggestion is certainly valid and appreciable, the reason why there are rarely primers for content about R (specifically) is that the intended audience is primarily academic, where the audience is already familiar with the technology. if you take an applied statistics class, you'll learn how to use R there.

If you're not already in the club, there isn't much reason for you to join it unless you're leaving industry to do scientific-level statistical analysis.

This isn't me saying "Mind your own business!". I'm just giving the perspective of the writers for most R content.