Lately, I have seen again lots of downvotes on questions and answers without any comment to explain why. For this reason, I have decided to reopen this debate.
It's not the first time that this happens in this site but, since there is no Meta post inviting to discuss it (or at least I haven't seen it), I decided to write one. Lately, specially on answers, I have noticed a proliferation of downvotes without any comment to explain why. In general, I feel that this behaviour is not very constructive for the site for the reasons explained in this Meta question: explaining why an answer in being downvoted encourage the poster to improve that answer. It can even encourage that user to write better answers in the future. I'm referring to the main site: downvotes in Meta are different.
Of course there can be some exceptions to this "rule" (in fact, it's not a rule, because every user is free to downvote without a comment, it's just an invitation from me). For instance, if one finds an answer that is spam in a very evident way, it's no worth writing a comment to say "we don't want spam in this site". In the same way, when an answer is of very evident low quality or an user has repeatedly shown an agressive or rude behaviour whenever anyone else criticise their posts in comments, I think there is no need to leave a comment to explain the reason of a downvote.
I would like to have your opinion about that and see if you think we should/could do something to discourage that practice.
[In addition to this, speaking specifically about answers and always in relative terms, I have the impression that, lately, the amount of downvotes is relatively high whith respect to the total amount of upvotes on answers. I sometimes wonder: we are really doing so bad in comparison to the past? I know this is another subject that maybe should to be asked in another question. I don't do it because I'm not sure if this is really that way or it's only a subjective impression.]
I would like to add that, according to my own experience, downvotes to answers without any explanation often leads to perplexity the OP and other users who use the site to learn Italian, because they remain wondering about what is wrong in the answer. And I fear this perplexity can sometimes cause someone to not come back to ask again (I've seen some instances of this behaviour on this site, but I'm not sure at all if this was a reason for it).