This is absolutely true and a main reason why you will see a lot of Pikachu faces in r/de after a German election. This is true for most subreddits which are touching on topics that in some form or another promote tribalism.

Such topics tend to naturally create opinionated flame wars, politics just being the most obvious example, but the subreddit mods often take a side even though the subreddit may advertise itself as the general hub for the topic.