You're right to point out the absurdity of dividing the universe of people into two groups: white and non-white or white and "POC." But humans have evolved to be suspicious of those who aren't in their tribe, who are different. We are naturally xenophobic. We reflexively divide the world into "Them" and "Us." There are cultural cleavages like sexual orientation and religion that divide us, but in the US, skin color continues to be one of the stickiest and most powerful dividing lines. "White" and "POC" are words we use to discuss this powerful force in our culture. White people would still, often subconsciously, divide the world into "Them" and "Us," "whites" and "POC" if we did not acknowledge that it's happening. To understand and respond to the phenomenon, we need words like "POC" to describe it.

Of course, "POC" was first used in a Western cultural context, and it may not translate in a straightforward way to an Asian context. I am sure racism also exists in Asia--xenophobia is a universal human weakness--but it may require different language to accurately conceptualize and the dynamics might be very different. It also might not be nearly as pressing of an issue as it is in the US. I don't know.

But if you've never heard the term "POC" before, you're clearly not familiar with the racial dynamics in the US. I would encourage you to learn more before dismissing a term as racist or judging the BLM movement in the US. I can't speak to the activists in Asia you mention, but I assure you BLM is a very much needed movement in the US.