Regarding Website Policy
Well, Merriam-Webster wasn't quite the reason I did it, so much as an ex-post-facto reference. I reacted upon seeing the word because I know it is policy to avoid them, and it is a somewhat urgent matter that is most especially applicable to new questions.
In response to the question Do we really need to add "NSFW" in question titles? Jeff Atwood wrote:
No, but we do ask that you mildly censor question titles because those can show up on the Stack Exchange homepage and other places where seeing an extremely vile curse word is definitely not welcome.
In the body, and the tags, you may do as you see fit.
(for prior art on this, see the "breasts" question, etc)
MetaEd also referenced this policy somewhat later on in Censorship of offensive questions a few years prior to his election:
In reality, the decision to censor titles is not open to debate. It is site policy, established by the business which owns the site. See the third question, "Should EL&U be removed from the multicollider, etc.?", where the site policy is clearly articulated by Jeff Atwood, StackExchange CTO. (And that is perfectly appropriate. It's their site and they can establish whatever policy they think is wise.)
One of these other places is twitter. Did you know your post was automatically featured on twitter ten minutes after I made the edit? Your post is going to reach widespread audiences and different people are going to have different opinions on the subject, and it is probably better safe than sorry in that regard.
Regarding the "'breasts' question" Jeff probably means this one, which suggests at one point the community even questioned the use/mention rule. If even a question containing the word tits was once considered questionable enough to be deleted for being offensive, then it stands to reason that damn is also off the menu.
Regarding how I edited the title, and only the title as per the guideline, I followed a practice I observed before of editing out the middle two letters and using filler to fill in the blank. It is relatively difficult to actually find examples because the symbols used, which are usually asterisks do not appear in search results. However, you can see one such example here: Etymology of "sh**hole"
Also, please note that not too long ago we were discussing Jesus H. Christ: so objectionable as to be deletable? with the following quotation from user Peter Shor:
The H. was inserted to avoid committing blasphemy by saying Jesus Christ. It's the same phenomenon as replacing damn with darn. So Jesus H. Christ here is presumably not the son of God but just somebody else with a very similar name.
Peter seems to suggest that he was trying to censor himself, and by using analogy with darn he is suggesting that damn is also worthy of censure. Granted, this was a use/mention violation, rather than a title question, but this represents prior indication that the word is considered offensive to the community.
Regarding General Offensiveness
I am having a relatively difficult time finding what I consider to be good reference to what are euphemistically referred to as four letter words. Damn is certainly among the list. The proposition lacks much contemporary dictionary support for my claim, but they do not even mark fuck as offensive. However it is worth note that there are many euphemisms for the term, including most famously dang and darn.
Here is what Wikipedia has to say on the subject of Four Letter Words:
The phrase four-letter word refers to a set of English-language words written with four letters which are considered profane, including common popular or slang terms for excretory functions, sexual activity and genitalia, terms relating to Hell or damnation when used outside of religious contexts or slurs. The "four-letter" claim refers to the fact that a large number of (but not all) English "swear words" are incidentally four-character monosyllables. This description came into use during the first half of the twentieth century.
Common four-letter words (in this sense) that are widely considered vulgar or offensive to a notable degree include: cunt, fuck (and regional variants such as feck, fick and foak), jism (or gism), jizz, shit, twat and tits. Piss (formerly an offensive swear word) in particular, however, may be used in non-excretory contexts (pissed off, i.e. "angry", in US English and British UK English ; pissed, i.e. "drunk" in UK English) that are often not considered particularly offensive, and the word also occurs several times with its excretory meaning in the King James Bible. Several of these have been declared legally indecent under the United States Federal Communications Commission (FCC) TV and radio open-airwave broadcasting regulations.
The term Four Letter Word is also defined in the Urban Dictionary.
Phrase that refers to any number of "bad" words, often seen in forum posts. Can mean shit, fuck, damn, and even other non-four-lettered-words such as ass and bitch. Can also refer to the basic four letter words with suffixes (ie "ed" "ing"). Usually said by some religious freak or ten year old that will get in trouble if their parents see it.
Damn man, that shit is fucking awesome! That bitch totally deserved it!
I could've understood what you were saying without all the four letter words…
One instance of the phrase I am particularly familiar with can be found on rules of the Caves of Narshe forums, where four letter words are forbidden under section 2 B of its rules. While their rules are not our own, I feel as if mentioning this provision can help to gauge the acceptability of such words on the web.
There is also a book entitled Damn!: A Cultural History of Swearing in Modern America By Rob Chirico © 2014 which capitalizes on the word's iconic status as one of the bad word for recognition:
Swearing, cussing, or cursing, out of anger, excitement, or just because, is something most of us do, at least to some degree. Turn on the television or open a magazine, and there it is. Damn! is an insightful and entertaining look at our evolving use of profanity over the last half-century or so, from a time when Gone with the Wind came under fire for using the word "damn" to an age where the f-bomb is dropped in all walks of life. Writer and artist Rob Chirico follows the course of swearing through literature, the media, and music, as well as through our daily lives. From back rooms and barracks to bookshelves and Broadway; and from precedents to presidents, the journey includes such diverse notables as George Carlin, the Simpsons, D. H. Lawrence, Ice T, Barack Obama, Nietzsche, and, of course, Lenny Bruce. If you have ever stopped and wondered WTF has happened to our American tongue, don't get out the bar of soap until you finish Damn!
This book also quotes Gone with the Wind's infamous line "Frankly my dear, I just don't give a damn!" which was quite a powerful line.
To be fair though, the word is not one of the words banned by the F.C.C., it only warrants a PG-13 rating in a film and the associated press accepts it, however they seem to advise only using it in direct quotations, and their blog article Too Vulgar to Print by Tom Kent from April 9 2014 notes that although the A.P. advises on spellings for the word now, even just a couple of decades ago that the word would have been considered unprintable. So what seems to have happened is that people became desensitized to it. However it is really quite borderline.
However, to be honest, my prior citation of Merriam-Webster was just an ex-post-facto reference. I acted upon my naturally accquired understanding of the word first.