I've written about this extensively over the years:
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...
https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme...
If you look over that material and still have a question that hasn't been answered, I'd be happy to take a crack at it.
The short version is: (1) some political overlap is inevitable* and ok, but (2) even in those threads, battle-style or flamewar-style comments are not ok, and (3) using HN primarily for such purposes is not allowed and we ban accounts that do. Your account has been on the wrong side of both (2) and (3), which is why I replied to you.
It's a common perception that "HN is getting more political lately" but I think that's an illusion which goes back a long way: https://news.ycombinator.com/item?id=17014869. It's a product of sample bias plus random fluctuation.
* Btw, that is the answer to your question "why not ban [political] topics entirely"—it can't be done. For one thing, there's no agreement about what counts as "politics"; for another, many stories that are clearly on-topic for HN have political aspects. Trying to exclude the political altogether would actually be a surefire way to intensely politicize this place, as we discovered when we once briefly (for a couple days) tried an experiment in doing so. That was quite a learning experience.