Some of the SJW's realised that inconsistency in treatmen of white people. As a result we get such gems of wisdom as designating the irish and other ethnic groups as POC or making some complicated categories for what counts as "white" or "POC" in different countries.
Because simply treating people the same way regardless of ethnicity or sexuality is not an option and instead everyone must be placed in a separate (but not equal) category for the sake of being equals.
They seem to do that because they're so hardcore about having an American-centric view of racism that they simply can't let go of their prejudices when they can try to fit them into the world. Instead of realizing that "white vs. POC" is a bullshit way of determining racism and doesn't match reality except in very small areas of history in certain places, they try to create more complex distinctions of what a white person or POC is so they can keep using their crappy system.
The irony is that Tumblr's SJ community preaches about not speaking over minorities/marginalized groups about the issues they face and their personal experiences (which generally isn't a bad policy, but I've seen it taken to ridiculous extremes), yet many of them are all too willing to abandon that principle when it comes to people living outside of the US, North America or white-dominated westernize nations and their own lived experiences.
Reddisred is one of the more glaring examples. She's deflected plenty of legitimate criticism with "white people don't get to comment, you're speaking over me!", including using this in response to people who called her out for saying that all white people are ugly, stupid and similar remarks (which is doubly ironic given that she's like 99% white herself), yet she was perfectly fine with dismissing non-Americans who tried to explain how discrimination works in their own countries, and felt the need to blabber on about French/English tensions in Canada despite clearly not knowing any of the history involved or the modern dynamics (not that the French/English stuff is all that comparable to racism, at least in modern times -- it wasn't too long ago that speaking the "wrong" language or having the "wrong" last name in certain regions could result in some pretty nasty prejudice -- but it really isn't an American's place to dismiss it as "infighting between white people, so who cares?").
Most of them aren't as extreme as Redd, but it's fairly pervasive nonetheless. The most recent example is probably the discussions about Frozen and the Sami, which were full of Americentrism and the dismissal of comments from people who actually live in Scandinavian countries, often on the blatantly hypocritical grounds that "You're white and not Sami, so you don't have the knowledge to discuss this!" Because, y'know, Americans are clearly better authorities on the subject than someone who actually lives in a Scandinavian culture.
