Why do you think the reason needs to be explained at all? Every site that uses an up/down vote system has pretty clear guidelines on how they are meant to be used, so either the user is voting according to those rules, or is using it as a like/dislike button. Commenting is typically reserved for contributing to a conversation, and in most instances, justifying a vote ends up being either noise, or comes off as complaining about Internet points.
No one reads any guidelines even if there were any. Do I up- or downvote in this community if I agree to a statement? I just think it would be helpful to know why a post meets so much rejection or consent. I of course get that Lemmy is a reddit clone. But do we really need to make it all the same? I don't think that the most upvoted post on the frontpage is the best post or most usefull in that timeframe. It's just the most upvoted post for a majority of people that do not contribute much but up- and downvotes. This is a Lurker-centric system. But I don't think that there are enough contributors that they would put up with this (+ there are no benefits to do so whatsoever). I just think the merrits of a social media site is it's content. I don't feel that there is much appreciation on here for that.