With respect to this specific example, I'm with you on the mention of lintr, but I think it's worth pointing out that the description of the article (which is under the header Using the RStudio IDE is: This article outlines the features available in the IDE. So, to say "[i]t is deceiving" seems somewhat harsh, as it implies deliberate or reckless intent (at least to anyone who's gone through an L1 book 
).
I think @jennybryan's Happy Git with R is a great example of a write-up that covers a bunch of options in addition to the integration of Git with RStudio: Chapter 8 Install a Git client | Happy Git and GitHub for the useR. That said, I think it's a big ask for every support article to act as a full-blown feature comparison (especially given the rapid proliferation of IDE options and integrations these days— which, like you, I think is a great thing). This, of course, is not the same thing as acknowledging the hard work of others that underlies the content, which should absolutely happen. The challenge is to strike a balance with the when, how, and where to do so (e.g. the tidyverse, of course, cannot exist without base R, something I say every time anyone brings up what I consider to be a false dichotomy— however, in the package release posts I've written, I don't open by reiterating that fact every time).
I've only been with RStudio for a few months, but, like Jenny mention, I'd say the RStudio employees and active user community are 100% with you in wishing that people better understood the difference between R and RStudio. (I'm pretty sure that, just yesterday, I referred to Chester Ismay and Albert Kim's awesome disambiguation chapter in their book 3 or 4 times!)
Folding the couple examples for convenience:
Summary
Loop not working, maybe due to Package ‘grid’ is not available (for R version 3.1.2) but I am using R studio Version 1.0.153? - #2 by mara
Issues Updating
I think much of what you're describing is a tension that exists when anyone uses a GUI, and I think the IDE developers work extremely hard to try and build in transparency (e.g. with the object inspector providing the equivalent code to retrieve the same object as you click through).
If/when you think something is lacking in acknowledgement, please speak up. I think the most productive means of doing so is by opening an issue or submitting a PR, when possible, or contacting the author of a post. I think this is certainly a productive thread/discussion, but, given that (in my experience) errors of omission aren't usually born of ill-will, I think corrections would be valuable, especially since it's often hard for "experts" and/or writers to see what's missing, since they understand the knowledge tacitly.
I haven't used ESS, but I didn't start using RStudio until ~2014/2015 (it didn't exist when I first started using R in high school). So, my experience of RStudio has always been about interface (and I likely don't use many of the GUI features I would if I'd been in RStudio from the start). But, my goal in using RStudio, and sharing what I do with it to others is never to obscure the existence/independence of R the language. I can only speak for myself, but I think an effort toward transparency and disambiguation is mutually beneficial. 
EDIT: The below ⇩ has now occurred! 
!
Actional feedback is always ideal— so I'll look into seeing if we can update that support article (I genuinely don't know where that part of the website resides 
).