As someone else mentioned, a lot of this is related to bots basically pulling & posting from RSS feeds, but even aside from that, it's the next easiest type of post to make outside of shitposts tbh. There's always something happening that's being reported in the news to share a link to, and there's always something going on with politics.
Other subjects also have a lot going on, e.g. there's also arguably a disproportionate amount of tech news being posted, but some other subjects take longer for anything of note to be shared/posted about, whether that's scientific research or entertainment. Books, movies/shows, music, games, they all take longer to make and there's not a ton many of them are allowed to discuss or share during the production process, so not as much to share or post about until the run-up to release, & after they're released.
Besides all of that, I think a lot of people are still figuring out what they even want to post & discuss here outside of news/tech/politics/shitposts and meta-conversations like this.