Maybe HN (and the web) has become less US-centric and more global? In Europe the issue is marginal to say the least, in Asia I believe they don't even consider it news-worthy, and so on. The opposite of "defining" for most of the planet.
Those of us in browsing HN and tech news in India find the inundation of BLM posts unrelatable. Tech and product is something people across the world can relate to. US-centric political issues are not.