That's a common misunderstanding of HN's guidelines; what they say is that most stories about politics are off-topic, and of course most != all. This has been the case for a long time—see https://news.ycombinator.com/item?id=4922426 for example, or https://news.ycombinator.com/item?id=17014869 for tons of other examples.

The question of how/where to draw the line is tough, but it's also one that we arrived at a relatively stable answer to a long time ago. I've written about this a bunch: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so....

I'm not saying we always make the right call—we don't, and anyhow people always disagree about what the right call is. But the underlying principles are at least pretty clear.