Fannish culture has a lot of rules and codes of conduct that develop in response to the needs of fans and are subsequently enforced - cutting picspams for dial-up users, marking content as 'not safe for work', warning for spoilers. And we all agree that those are good, considerate things to do, and when someone messes up you can usually guarantee that the first few comments they get are along the lines of 'dude, lj-cut, use it!' or 'a little warning for graphic content would have been appreciated, I'm checking my flist with the kids in the room!', etc. We consider all of that to be common courtesy, and most people abide by it.
So I'm trying to get my head around the idea that there's a big difference between saying 'hey, this uncut post is super spoilery for people who haven't seen last night's episode yet, you should cut it' and 'hey, this story might be very triggery for survivors of sexual violence, you should warn for that'. Adding the warnings is about the same amount of effort in both cases, and wow, the second kind of sounds like the one more worth avoiding.
For discussion of what, exactly, triggers are like, see the below, which outlines what exactly we're talking about when we're talking about triggers, for people like myself who are fortunate and don't have them.
impertinence: Sexual Assault, Triggering, and Warnings: An Essay "Warning: Very explicit discussion of sexual assault and the nature, anatomy, cause & effect of triggers. Is itself triggery."
Being triggered is not like being spoiled, or being embarrassed because you opened up adult fanart in a public place. It's also not like being squicked or being made uncomfortable by a theme. We all have things we don't like to read about, and that's what the back button's for if we discover the story is going to go along those lines. That's very different from being triggered in the way that impertinence describes. People with triggers also aren't asking for everything ever that could possibly trigger a specific person to be marked; rather, the basic few, the stories that do feature sexual violence and consent issues. It's that baseline and that level of triggering that's under dispute here. Apparently, warning for noncon in order to ensure people who'll be triggered by that requires too much sacrifice of artistic integrity. Which, wait, what?
Unless I've missed something, headers are meant to do one thing: provide the reader with information. The vast majority of the time some of that header information does spoil elements of the story - the rating tells you whether there'll be sex scenes or not, the characters and pairings give you some details. Unless all you mark it as is 'title, teaser line, character a/character b, nc-17' and the story starts with said characters having sex, you'll probably have told your readers something about what's going to happen.
If a specific warning really is going to spoil your story (which is far from always the case), then you can create some sort of spoiler cut/whiteout for it, or you can have a blanket policy, clearly visible/linked to on every story you post that outlines what exactly you do and don't do with warnings. There are a lot of options here, and I am sure there is a solution for every writer -- also worth noting, where 'warning' may imply something negative about those who like to read stories with those themes, which I understand, 'contains' seems to work nicely.
Otherwise, if there's widespread disagreement about this, then I don't see how people with triggers can navigate fannish space very well, if at all -- all they'd be able to read would be stories that say 'warnings: none' on them (and when was the last time you saw that? the last time you put that in your header? I never do) or communities like some fic exchanges where stories won't be posted if they have content that isn't warned for. Or else, they'd have to research/check with a friend for every single story, no matter innocuous the title and summary might sound, however well you think you know the author, because if you don't know their warnings policy, it's your own fault if you get yourself triggered!
I really can't get my head around why anyone would want fandom to be like that. It's never going to be 100%, obviously, but I don't understand why it's a fannish faux pas to spoil somebody for an episode of a TV show, but it isn't one of similar universality to decide not to let potential readers know that your story could induce violent flashbacks in abuse survivors.
Posts by others that I've appreciated (again, content in the entries and their comments may be triggering):
again? we're having this debate again? by thingswithwings
The warnings thing by giandujakiss
This wasn't the post I intended to make today by annaalmode