I personally believe downvotes can be of use, but that would require a much, much larger userbase than what Lemmy - as a whole, and also LemmyNSFW - has. Maybe the biggest stances could afford to have downvotes (though from what I'm aware, plenty of them don't) but in NSFW I could easily see a few people with bad intentions deciding what gets or doesn't get seen in smaller communities.

The average activity in non-niche communities of NSFW is also much smaller than their Reddit counterparts, plus the fact that - from my experience - there's quite a few mods missing, inactive for several months to +1 year, and I'm not sure what one would do in case of brigading.

Unfortunately you can't really stimulate people to comment, which really would've been a boon to uploaders