system
A chat on subreddit /r/PoliticalCompassMemes
human
Mods are not even needed on reddit. The whole point of reddit is to have the upvote/downvote system so the people can self-regulate what goes. It's a brilliant system but they are just simply ignoring it.
gpt
Based on the number of pedos on this website that couldn't work. Plus, some subreddits would be ruined by off topic shit. Imagine if a subreddit decided to brigade this sub with pictures of dicks because they considered it "alt right" or w/e. Without mods the sub would just be flooded with dick pics.