Reddit

It is majority bots. I got the groundhog day feeling too. So a few years ago I started looking at the account that post rather than the posts itself. There's a simple pattern. The account is registered but lays dormant for a couple months. Then it becomes active and starts reposting top ranked post of all time from subreddits. Their comments are copy pasted out of replies to old posts.

It's inexplicable why the real human users put up with it though. At some point the zeitgeist stopped having baseline expectation of content quality.

More recently there's a newer phenomenon where clickbait stories ("My (45M) wife (18F) of 5 years left me everything but the icecube trays AITA") are posted by brand new accounts. Except all those subreddits don't allow brand new accounts to post. So it must be the mods are selectively approving them. They are farming outrage with stories (most likely fake) meant to maximize user activity.

Probably the same reason people keep posting the same questions in tech subs over and over and over again.

There are a lot of people who need help/need to tell the world about something great to them, but few people are capable of or care to search previous posts.

Moderators removing duplicates often results in a bad user experience, especially so for new users who haven't seen that post tens of times, so it's often allowed to a certain degree.

The comments have gotten just as bad too. Trolls and Bots everywhere. No moderation. Also, the voting system works well when it's mostly sane and intelligent people there. Now the dumbest comments get upvoted super high and any long critical, intelligent responses get downvoted to oblivion.