It is my observation that there are, broadly speaking, 2 definitions of "racism" floating around in the USA these days.
The first is mostly used by people who have lived in a fairly homogeneous environment (ie mostly people of their race & cultural background, which in the USA happens to be white and christian), and it is a very strict one. Murdering a black person while shouting "all black people must die!" would undeniably be "racist" under that definition, and so would a law that says there must be separate facilities for white people and people of other races. However, that definition does not encompass much in the way of acts that do not blatantly qualify as racist.
The second definition, used mostly (but not only) by people who are not of the dominant racial or cultural background, defines racism as a broader system of interconnected pieces (some historical, some cultural, some legal, etc.); some of them which might not appear strictly racist at first, but when observed within the broader scope of the system they function within, contribute to a general systematic alienation of the population based on racial or cultural features, or in other words, "racism".
People who function with the second definition might find the linked article "racist" in that sense, because while it is a well documented article, it presents a picture of the US that is lacking many speakers of American-English, the vast majority of them non-white. Of course, that map is a flawed representation in the first place - dialects are not distributed neatly along smooth lines as depicted. But it is flawed in a way that totally erases the existence of many speakers of American-English (unless one wants to make the argument that these communities do not speak American-English, which I think most HN readers can see as absolutely silly). The map, like any other map, is a flawed representation; but it is one that, under this definition, could be said to be flawed in a racist way. This does not mean that the author is racist; merely that the work was produced within a dominant homogeneous socio-cultural context, that many take issue with.
The USA is currently undergoing a deep identity crisis, where the hegemony of the cultural majority is being challenged by people who identities have been ignored over the centuries (some due to genocide, some due to slavery, some because they were just poor immigrants at the bottom of the totem pole, but whose descendants are very much native to the USA and are confined to ghettos, etc), and who are now able to express themselves due to the new forms of media that have emerged. Many people living outside of the US (and many within) do not have much of an understanding of this situation, either because they have not been exposed to it sufficiently, or because they outright deny it (for one extreme of it, see Steve Bannon's reaction when an interviewer says that all Americans except for Native Americans are immigrants [0]).
A similar phenomenon is also happening with the notion of "sexism".
Calling something "North American Regional Dialects and Accents" when they really mean white north american regional dialects and accents strikes me as a racist title choice. Black people are not an outlier, they are an integral part of the society and have been for hundreds of years. The assumption of the title is ridiculous.
