I mean the question is not a bad starting point to understanding how white supremacy functions but I would not be asking it to 3000 hitlerites
Don't worry most responses are "see black people can be racist too and a lot of the time are more racist."
Yea you could use it to show them the one drop rule and how white supremacists wrote into law to consider anybody black if they have a single drop of black blood and how that shaped our societal perceptions.
Or, like other people have figured out in that thread obviously cus black people are racist against white people.
As a member of the biracial delegation, I can answer this. You're neither considered black nor white, and members of those delegations feel the need to remind you on a constant basis.
Definitely. It is very revealing of their own biases and the biases of their immediate circle.
Had a mixed classmate in coklege and everyonr called him neopolitan becayse the entire class besides him was 
Reddit is a cool place because someone with a post history that sounds like Mein Kampf written by a tik tok teen can post a question like this, and thousands of 30+ milinneals will earnestly debate like they're both hosting and guest appearing on a topical interview podcast.
I was thinking reddit is a big website, the question reached the front page so there could be a few decent responses but no. When the responses are not racist they are low quality. Top response is "hmm makes you wonder why Obama is not considered the first mixed president" 
Smh 
can't even get the format right.
"What is the One-drop rule." "Ehhhh, close but not the one we're looking for."
"What is racism." *blong* "That's it."
It's just that they asked redditors, the better comments are slowly making their way to the top but a lot of the top comments are garbage
Edit: they also went to r/ask, going to a sub like r/askhistorians would have given much better answers
Firstly, it's not a universal thing. Race is a social construct, who is considered "white" or "black", or a member of any other racial group, changes depending on where you are in the world, and the culture and history of that society and country. In South Africa for instance, mixed race people are considered, and self identify, as their own ethnic cultural group, known as the coloureds (not a racial slur in South Africa). Many things affect this, from apartheid racial classifications from the past, to cultural differences from being raised in a certain home environment. In other parts of sub Saharan Africa, people who would be considered black in the USA and/or the West, are considered mixed race or even white.
As for why that's the case in the US, one just has to read up on the "one drop" rule in the United States, and it's ramifications on modern day understanding of race in US culture and society.
This could be some kid just finding out about how racist their country is and is confused and horrified and just doesn't have the language to phrase it in a way that doesn't sound fashy.
Thankfully the brains trust at reddit will set them right and tell them all about how it's actually the minorities that rule the country and they should watch a bunch of Jordan Peterson and Ben Shapiro to explain it to them.