r/childfree is one of those subreddits that perfectly proves the problem with Reddit. Because of the upvote system, subreddits will eventually trend to being the most stereotypical and extreme example of the subreddit's purpose. It's not enough to say "Eh, just don't really feel like having children", because that won't get you the updoots, someone has already posted that before. So from there you have to go to outright celebration of how you've actively prevented yourself from having children rather than just passively, then eventually it reaches this point, where they're saying other people's children need to fuck off and die.