Please note that expletives are not allowed. If you use expletives on this site, you may be issued a warning or a suspension.
So, that's basically that.
The rules are actually pretty arbitrary
Trawling through the archives on this issue gets a bit annoying. The discussion has come up on various SE sites in addition to Meta (mostly when it was SO Meta). As far as I can tell, Jeff Atwood's original arguments for a blanket ban revolved around stuff like automated corporate blacklists.
On Meta, the highest-scoring answer is "Keep profanity to a minimum," followed by "Don't," followed by "It depends." Clearly the community is generally in favor of not putting cusses everywhere, but not everyone's all that excited about keeping a hard line.
Personally, I think that little line in the blurb serves as a useful deterrent from just swearing casually. And... that's about it. I find most of the actual arguments presented to be pretty silly:
Where is this draconian nanny software? Is it real or hypothetical? What kind of sophisticated software is it using to decide that "Brainf---" must always be censored in text but it's okay to put its full name in a URL, or that it's okay to ask questions about "dirty" words on English Language & Usage Stack Exchange?
If swears are a big deal, where's the filter on the post button? It'd be pretty easy to have a quick popup that says "Hey, this looks like cusses, did you really mean to post that?" without inhibiting the operation of the site.
"What about minors?" Forget the realities of language use and exposure: if we literally edit out everything, we're restricting "bad language" much more stringently than the "PG-13" or "TV-14" guidelines do.
The MPAA/FCC regulate swears. That's true. We're clearly not applying their standards, though. That's fine, because their standards are pretty stupid. Right now the policy seems to be "I know it when I see it." Which is fine and all, if it's just going to be based on someone's gut-feeling about where the line is ("sh--" is banned, but "d---" and "wh---" are fine; and another one of Carlin's "seven dirty words" appears on the site like 50 times), then do we really intend to enforce the "AND WE WILL BAN YOU FOR SWEARS MAYBE" part of the code of conduct?
"Professionalism" is a bugbear on SE, but note what the Behavior page actually says: "Be honest" and "Be nice." "Professionalism" also isn't a one-size-fits-all thing. In the context of the answer that prompted this, I consider a bit of frank language to be entirely sensible when discussing a charged, emotionally complicated situation affecting a group of friends playing a hobby game involving fictional rape. Keeping the whole response detachedly clinical would, in fact, have made it a worse answer, because it's not an answer about detachedly clinical things.
"Cussing is offensive!" Let's be very clear: some people don't like swears, even the ones that see widespread use every day. Some people dislike them enough to say "I'm offended by this." But some people get upset when you end a sentence with a preposition. Some people get ticked off when the answers to questions keep assuming you're playing D&D just because (in this case, "some people" is me! all the time!). Some people find the fleshy skull-robots in the site banner kinda gross, I'm sure. Should the site bow to those people or not? There's no One True Answer, and you can't always please everyone. This is a choice you make.
Some details from the comments:
Profanity/vulgarity is not obscenity. This is a distinction that actually matters sometimes.
Many common vulgar words are not attacks. Analogies to bigot-words and bigoted ideas are entirely unwarranted. Group attacks should be always unwelcome, no matter what their form. If you're concerned about inclusion, forget about typing cusses into the search box and be more assertive in removing microaggressions.
"It's lazy!" is empty moralizing. It's just a way to take an argument about propriety and wrap it up in the "Protestant work ethic" in order to make it easier to swallow to American audiences. I'm pretty sure the hobby-themed SEs are practically sustained by laziness, anyway, if you count all the people posting from work.
Which isn't to say that the rules themselves are bad, necessarily. The justifications presented, however, are all over the place, and most of them are pretty poor. Which makes it hard to tease out how to effectively apply the rules in order to improve the community rather than arbitrarily applying them because that's what it says on that one page there — which, no offense, is what we seem to be doing right now.
You can me point to site policy (or you can just go and change it without appealing to site policy, and even if I didn't know the site policy I probably wouldn't bother to change it back) and I'll accept the change, but I really don't think the question that prompted this is an example where site policy is actually doing anything substantive to improve its content. It's just minutiae, like cleaning up some typos.
Let's apply the rules anyway — constructively!
Stack Exchange gives users plenty of tools to improve each others' content. So, improve away! Just pay attention to what you're doing so you don't hurt anything while you're trying to help. Specifically...
When editing an post because of cusses:
Improving word choice is great. If you think you can improve word choice as part of other edits, do it! There's very little downside.
If you're editing direct quotes, make sure you add the appropriate markings so it's clear the text has been edited. This is just how you comply with basic rules of citation and attribution. E.g.
The rules on page 45 say "Your [stuff] breaks whenever you roll a 1." to show that "stuff" was your own substitution.
Bowdlerizing stuff with underscores and @$@# or whatever actively hurts readability. If you're having to do this, your edit is hurting the content more than it's helping. Step back and find another way! Short of a direct naming issue like "Brainf---," there's absolutely no reason to ever clutter up an answer with ugly censor-marks.
When writing a post:
I dunno, try not to cuss?
Don't cuss at other people. Or attack them without cussing at them. Because that's verbal abuse, either way. Not cool, ever, at all.
When reading posts:
Edit things that stand out as wrong to you. If you notice cusses, that's cool, edit away. If you don't notice cusses, don't waste time trying to train yourself to notice them. The issue will work itself out, just as easily as typos.
Everyone should put effort into looking for actual verbal abuse, stereotyping, exclusive language, or nasty underlying subtext. Because that's what actually matters when building an inclusive space.