There aren't, but it's worth thinking about what a vote does. In Lemmy and similar systems, comments with higher scores are listed first and seen by more people. A downvote means "fewer people should see this".

Now perhaps you just believe fewer people should see things you disagree with. That's not my position, but I won't try to talk you out of it here. If that's not your position, however and you instead believe civil, well-reasoned discussion between people who have different viewpoints is valuable, then using votes to simply express agreement or disagreement will not serve to promote such discussion.