I see where you're coming from, but this to me seems more like a property of the fediverse than an issue with Kbin in particular. Right now, anyone can make an instance and choose to show downvotes. Someone could make their own instance, gather downvotes federated from other instances, and make a list of who's downvoted who. Being on an instance that doesn't show downvotes doesn't hide your downvotes from everyone — just you and others on instances that don't show them.
On this end, I feel that Kbin instances are just being transparent about the publicity of your votes. If anyone can see your downvotes just by looking at an instance that shows them, I think it's important that people are aware of that. Showing public votes is sort of telling you, "Hey, people can see how you voted on the fediverse," and that's preferable to pretending that nobody can see them.
At the moment I personally am a fan of the limited downvote federation because I do think it acts as a hivemind barrier;
I think it's a lot less straightforward than this. While it definitely drowns out the "hivemind" of the wider fediverse, it also creates a bubble within your own instance. If a lot of people outside of your instance think you made a bad comment but few inside your instance do, limited downvote federation creates an inaccurate representation of what people think.
Additionally, having downvotes but limiting their federation makes them extremely unintuitive and only serves to further confuse new users. It's actively misleading—you'd think that if you see 0 downvotes that nobody clicked the downvote button, but that might actually be 5 people or 10 people or 30 people. At least if you don't have a downvote counter at all, it's clear that downvote functionality just isn't recognized on the instance. I'd much prefer that over a straight up incorrect counter.
Overall though, I think the problem is how the downvote was used (on Reddit, at least) was not conducive to discussion.
I agree that there's a big problem with how downvotes are used. I personally use downvotes if something is:
spam
straight up hateful
completely off-topic
a nonsensical take that the poster doesn't support
In other words, if something isn't a reasonable contribution to the discussion, I'll likely downvote it.
However, lots of people seem to use the downvote button as a disagree button. I see this less on kbin.social than I do on other instances, and that could be a potential reason to not federate downvotes. If downvotes are used differently on kbin.social than on other instances, then I can see it making sense to not lump them all together. However, that only makes sense if people on kbin.social aren't using the downvote button as a disagree button (which they are, just less so than on other instances). And even still, there's the problem of an unfederated downvote counter still being misleading.
Rambling aside, I see three ways of handling this:
Remove the downvote button entirely.
Remove the downvote button, but replace it with reactions that people can use ("This is spam," "This is hateful", "This doesn't contribute to the discussion," etc.). If other instances adopt this set of reactions, reactions from those instances could federate.
Keep the downvote button and federate downvotes.
I don't like #1 very much because then you don't have a great way of indicating spam, hateful posts, unhelpful comments, etc. outside of reports that only moderators can see. #2 seems really nice, though both it and #1 come with the downside of filtering out negative feedback from instances with downvotes. #3 is also good, though it comes with the problems of downvote misuse.
This is a good time to start a discussion on how it should work on kbin.social
A while back, I made a thread on /m/AskKbin about this. While it's not solely kbin.social users, there's still a lot of good input, and you could use KES to sort through those who are and aren't on the instance if you want. My two cents are that it's important for downvotes to exist, be federated, and be shown separately so that (A) people can easily express that they feel something doesn't helpfully contribute to the discussion and (B) similar expressions from other instances aren't drowned out.
Downvote federation only applies to remote threads from other instances, without affecting local threads
To be clear, what exactly do you mean by this? Does this mean that downvote federation is one-way (i.e., that downvotes federate from Kbin instances but not to Kbin instances)?
I think it'd be simpler to just change the block button so it does that. Adding a new "filter" button would lead to newcomers being confused on what the difference is. Besides, I don't think there's much benefit to being completely unable to view a magazine.
As someone on kbin.social, I'm not seeing it. I saw a comment in a similar thread saying that moderation done on Kbin doesn't federate to Lemmy instances, and I think that's the culprit here. @ernest (the Kbin dev) is working towards a full release, and I hope that it might fix this issue—or at the very least, that it's dealt with shortly after.
EDIT: Yeah, I looked at @science from lemmy.ml, and my God is it awful. This really needs to get fixed ASAP.