The closest to a "both sides" that's reasonable for this is, there are people who wonder, "Isn't it bad to fill your head with horrible stories? With violence, with rape, with torture... it can't be healthy to be obsessed with such distressing and maybe disgusting content."
And. Sure. It is not good to wallow in stories about Horrible Stuff.
You can't tell from someone's online habits if they are "wallowing" in some kind of content. Not even if they leave kudos on tons of it and nothing else. You just don't know how much time or mental consideration they're giving to the stories. You don't know how those stories are affecting them.
While there are people who have problems with obsessing over dark content, there are also a lot of people who use dark content for other reasons: To process their own traumas is the one that gets mentioned the most. It's also used to sort out complex emotions, to understand the motivations of unpleasant people they've known (especially if those people got better, and they want to figure out how they could ever have done bad things), or just to explore the possibility of human actions in a setting where no real people get hurt. There is value to this content.
It is not your job (not my job, not AO3's job) to force people to Not Do Bad Things. If someone is damaging themself by wallowing in horrific content... that's their choice. If they're a child, it's their parents' job to manage the media they're exposed to. (When I had young kids, I sure as hell did not want randos on the internet deciding what was acceptable for them to see.) You are not the thought police.
There is no variant of "this content should be banned" that doesn't play right into the alt-right evangelical Christian neo-nazi TERF agenda.
And there is no variant of "the people who make or read this content should be ostracized, bullied, and threatened with real-world violence" that isn't just hate speech and punching down at marginalized people.
The closest thing to a valid "anti" stance is "I don't want to see any of that horrible stuff; I don't want it to be welcome on the archives I read at; I don't want people who like it in my communities because they creep me out."
In which case... be selective in what Discords you join, and don't hang out at AO3. Maybe get together with other people who share your tastes and set up an efiction archive (or mailing list, or Discord with google doc links) for the fiction you all enjoy.