[leibwiht]

It's more than just the absence of a like/dislike system, visibility of posts is directly determined by how much discussion they generate - for threads this means its position on the board stays higher for longer, so more people see it, and for replies the number of replies is visible while scrolling through the thread. This links agreement/disagreement with actual discourse (or, at least, communication), unlike e.g. Reddit where agreement and disagreement are done via voting, which doesn't contain any information other than the upvote/downvote itself. In systems like this, disagreeing via replying is actually suboptimal in terms of return on the labor involved with communicating this disagreement, because downvoted posts (posts people don't like) are less visible, meaning replies to them are less visible as well, even if they agree with the majority of the people downvoting their parent post.