Reddit's decade-old rule that you shouldn't submit more than 10% of your own content is one of the weirdest artifacts of that era, especially since every social media company would kill for good original content.
despite the loud complaints, many people on reddit don't really care abut original content. They want what is funny or big news or otherwise garners an extreme reaction. And when you can't find those, reposting the surefire hits works just as well.