A good forum design will only get you so far, the rest is up to the moderators. If you let bad actors in, it doesn’t matter how you designed your forum, they will poison the well and drive other people out.

Yes, well, the problem with hexbear was that it started with bad actors. As they made their true colors apparent to the lemmy community at large, they were increasingly defederated.

The best communities I’ve been in are in independent old-style forums. One of them is Tildes. Most of these don’t feature downvotes (or upvotes for that matter) and are honestly the better places to have discussions IMO.

Oh yes, my past experience is in old web forums as well. Those communities were more isolated though, they essentially existed inside their own bubbles. Unregistered users could read them, but not participate in any functional way, and typically the people that found them were looking for a community like that on purpose.

I've also experienced such communities becoming toxic due to the actions of individual moderators or admins, post voting not required.

Ultimately I think I agree this far - if you're going to disable voting you should do all of it. Removing only the downvoting is the YouTube path, the authoritarian path, the toxic positivity path.