My own tuppence worth... There's an Irish news website, the journal.ie that used to have a thumbs up and thumbs down feature. I thought it was great, and a given comment on an article might be net-positive or net-negative, which would give a good sense of what the crowd thought so to speak. The up vote/downvote was anonymous so there was no pressure at all, so it felt like each comments' judgement was truly merit-based. They got rid of it, and the comments section has since been infested by right wing bots (not because the option to down vote went away). I really disliked when they got rid of it though. Therefore I think on a platform like Twitter, a downvote option would probably be useful.
However, for a forum like this I don't think it would be. I think it would disincentivize people to venture forth an opinion if they thought it would be unpopular. It keeps things positive and constructive to have an option to give someone a thumbs up or a smile if you agree/like, or to engage with them in discussion if you don't. I think a band forum is different than Trump spewing some vile shit on Twitter or truth social or whatever, which should absolutely be open to being simply downvoted.
Sorry, that may have been slightly more than tuppence.