Yeah I can definitely see that being a threat model. In the gaming case I think it's harder because it's more of a general reputation system and it's based on how people feel while playing with you, whereas for a website every post can be reviewed by multiple parties and the evidence is right there. But certainly I would still expect some people to try to maximize their reputation and use that to push through content that should be more heavily moderated, and in the degenerate case the bad actors comprise so much of the userbase that they peer review their own content.

It's more like jury duty where the decision of one or a few people can have a huge impact (modded or not).