Disabling downvotes by server admins on Lemmy is dumb and does not make any sense.
By default, Lemmy allows downvotes globally. However, when a server disables downvoting, it is similar to using a feature that is usually reserved for enterprises and very small, non-federated communities.
If a user prefer to not see downvotes, they can disable it by his favourite client settings, but the rest of the community should not miss this functionality for the pleasure of few users.
I do not care enough, because here on lemmy.world it isn't a thing. But I see you're from lemmynsfw. I vaguely remember a thread where the disabling of downvotes was discussed and to this day I do not understand why people are afraid of downvotes on their wanking material.
They disabled downvotes because they want to encourage people to post porn of themselves not just to repost stuff. Getting downvoted for posting your own work isn't encouraging and essentially kills communities before they even start.
If ur posting shit u don't want to build a community on that. I recon they did it simply to push an agenda of unpopular crap that most people (on lemmy) dont wanna see ie dudes and fat chicks, they got downvoted for a reason. Now i guess everyone needs to get used to a liberal application of the block button.
Reposting is not a problem, it's an NSFW server, nobody will downvote repeated content. What was getting down voted were dudes and chubby women showing off.
I cannot affirm with certainty there is correlation, but the main page is far more diverse in people and content since the removal of the downvote, and constant reposting is not a thing I see (at least for now).
As I understand it, the reasoning is that someone posts a picture of their gaping arsehole and it gets downvoted because of the horrid hairy mole on the left cheek, it might dissuade them from posting pictures of their naked breasts — which might be more in line with the community's aesthetic sensibilities — in the future.
Which, frankly, seems kind of reasonable.
Lemmy does need more user engagement. Even if you discount the 99% of posts by repost bots, reddit's maggoty corpse still has one or two orders of magnitude more user engagement, which means more tits and gaping arseholes, even if some of them have moles. Anything that makes people more comfortable posting original smut (and other kinds of content, I suppose) here is welcome.
That said, I think this only should apply to posts, not comments, and only in specific communities. Downvoting gaping orange arseholes in political news communities, for instance, should not only be allowed but even encouraged.
(Personally I still downvote everything anyway; it might not affect the vote count, but it makes me feel better.)