Also: some people seem to get an amount of pleasure from pointing out repeats, as if remembering that something was posted before is knowledge enough to make them a better person than the poster, us all, or just the person they thought they were themselves. This is fine when something is posted far too often, or is reposted by a point-farming bot (presumably the users running such bots hope to use the reputation of the account somehow in future), but is often done overzealously.

The cheapest available model once you have Theory of Mind (the idea that the other things in the environment might be thinking like you do) is that they're you again.

The Smarties test (What's in this Smarties tube - look it's not Smarties, ok now what does somebody else think is in the tube?) shows that humans need a further step to discover that model isn't enough.

But it's still cheaper and it's pretty good. It will correctly predict that this person you've never met before probably wants cake not death, just like you. It won't reliably predict whether they prefer lemon cake or coffee cake. But it's a good first guess.