Great and very important article. Lots of good information, and it's nice to see more sources demonstrate and promote awareness of this issue. But there are a few things I would change about or add to this article.
The term "RG/BW" can be preferable over "RGBW", because it more clearly indicates that all four colors are not present within every denoted pixel. There are also displays that are WR/GB -- it seems Samsung makes the RG/BW panels and LG makes the WR/GB panels. But I would say it's reasonable to use the terms interchangably. The term "RGBW" seems to have been coined by Samsung themselves. Samsung was the first to produce these displays, and appears to be the primary driver/enabler behind the practice. We need to use descriptive terms, not potentially misleading marketing terms. I would actually suggest to do a Ctrl+H replace on that term throughout this article (edit: especially for the top preview text). This leads into the next point.
The laptop displays in question don't replace every fourth subpixel with white. They aren't RGB/WRG/BWR/GBW, they are RG/BW/RG/BW. They have only two components per denoted pixel instead of three, which is a further reduction in detail. You might be confusing this with the similar (but not identical) issue present in many of LG's "RGBW" TVs, which is RGB/WRG/BWR/GBW. http://4k.com/news/lthree-of-lgs-4k-tvs-offer-pseudo-uhd-and-a-raw-deal-for-consumers-uh6400-uh6100-uf6800-16649/
To drive the point home, I also always like to point out how displays such as 3840(RG/BW)x2160 aren't only worse than their full RGB matrix counterparts, they can even look worse than "lower resolution" true-resolution alternatives such as 2880(RGB)x1620 due to visual artifacts. They do this while demanding the same rendering effort that true 3840(RGB)x2160 would. And the "lower resolution" true-resolution displays invalidate purported "advantages" of RG/BW displays such as power savings, because the lower RGB resolution displays accomplish the power savings with fewer visual artifacts for similar effective sharpness, and without leaving the hardware to render the larger picture. ASUS and MSI actually moved away from 2880(RGB)x1620 to 3840(RG/BW)x2160 in a number of their product lines. This demonstrates the companies' apparent willingness to choose worse parts in order to sound better in advertising.
EDIT: I would like to add that, in the header, the phrase "While the concept is relatively straightforward, how manufacturers achieve native 4K resolution can be dubious." does not sound very good to me. I would change this too. The key point we want to make here is that 3840(RG/BW)x2160 does not achieve 3840x2160 resolution in a true sense. It is not "true 4K". What the matrix achieves is the ability for the display to be listed as 3840x2160 in the product specifications, and for the hardware+software to address the display as if it were 3840x2160. One might argue that 3840x2160 in luminance resolution is achieved, however there is no overlap in the hues that the alternating denoted pixels are capable of producing, so this technicality should be carefully considered before taking it at face value.
Feel free to contact me on reddit /u/edit1754 (/r/SuggestALaptop/ moderator) when preparing or finalizing articles about this, or about laptops that list 4K resolution in the specs. You can also email me (username at gmail), I just don't check email as often as I do reddit. I've done a lot of research on this, have refined some of my ways of describing this issue, and maintain a list of true/false high-res laptops in the subreddit's sidebar.
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