I recently learned that voting on lemmy is not anonymous. Anyone can get information about who has upvoted and downvoted a post or comment.
In combination with your IP, this is a massive privacy (maybe even physical security) risk. Also, people can target you for your votes.
Sadly, this is something where I would prefer Reddit over Lemmy. Big tech scrapes data from both places anyways, at least Reddit is safe.
Saying I disagree without explanation robs the OP and the community of varied conversation. To comment on an upvote would pretty much just be what the op posted. It also stops bandwagoning where people just downvote to get an inflated ego and feel they’re right while contributing nothing but hiding a comment (comment dropping off due to filters).