I definitely get where you’re coming from, but I really doubt that would turn into a problem if downvotes were generally disabled on Lemmy – after all, it’s not a problem on Lemmy instances that already have downvotes disabled.

One problem with downvotes on Lemmy is that people who browse All do have a real tendency to downvote posts in niche communities that they’re not even members of, and I’ve seen it happen a few times that smaller / niche communities will generally have a bunch of downvotes on their posts even though it’s not the members doing it and this is why some instances I’m on have specifically disabled downvotes.

It’s often said that downvotes shouldn’t be used for content you disagree with, just for things that don’t “add to the discussion” (whatever that means), but the reality is that that’s simply not how people use them. Only allowing upvotes means that generally the “Nazi-adjacent” stuff is still very low in sort orders because it doesn’t get upvoted as much as everything else, and it prevents knee-jerk downvote waves where unpopular stuff just gets downvoted because it’s already in the negatives so it must be bad. And remember that the putative Nazis can also downvote; what’s to stop them from mass-downvoting smaller LGBT+ community posts?

Also, on my other accounts I’ve had multiple cases of me pissing off eg. a Musk fan or whoever and they then go into my profile page and downvote everything – one fucking weirdo went far enough to apparently write a script for it so they could downvote all my historical stuff and all my new comments and posts as I made them.