Users flag articles. We don't always know why they flag them, but in this case I'd guess that it's a combination of the topic having been covered a great deal already and the articles not adding significant new information (https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme...). That means there isn't much intellectual curiosity in them, and intellectual curiosity is the purpose of this site.

Political articles are a borderline area for HN. There is inevitably some political overlap in what gets posted here. At the same time, if we don't do anything to contain them, political topics and battles and flamewars will take over the site completely. We moderate the site to prevent this from happening. One criterion we apply about political topics is whether the thread will merely be a repetition of what has been discussed before or whether there is a chance that the community can have a curiosity-inspired conversation about it. If a discussion turns into a flamewar or is extremely likely to, we are particularly likely to downweight it, because flamewars are the #1 thing that destroy this site and community.

There's more explanation at https://news.ycombinator.com/item?id=20013092 and https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme... if you or anyone want it.