I've slowly come to the conclusion that it's a form of opinion-shaping. A huge number of people aren't particularly interested in what's true, they're interested in what's _popular_.
For argument's sake let's assume it's 80/20, with 10% on each side of a topic very passionate for their side. By banning and/or rate-limiting the 10% you dislike in any issue you can sway the 80% to follow the other side thus "manufacturing" the consensus.
I don't think there's any distinction to be made between what's "true" vs what's "popular" when it comes to online discourse unfortunately. Confirmation bias is one hell of a drug, especially when combined with votes, flagging and reports.
For argument's sake let's assume it's 80/20, with 10% on each side of a topic very passionate for their side. By banning and/or rate-limiting the 10% you dislike in any issue you can sway the 80% to follow the other side thus "manufacturing" the consensus.