I'm adding more of an observation and rant (rantservation or obserant, up to you) to this.
Easy question promted easy "yes" "answers." I think moving a simple "yes" answer into a comment is a symptom of the original simple question, which might be okay coming from a relatively new user (and because it mentions
We Love Code!
The code was really the "answer" that was voted on. The fact that the API is both read and write seems like a preamble to me, though it technically answers the "can we?" question just like Dominic's original reply. Everyone loves code samples as objective, copy-and-pasteable demonstrations of expertise. My top voted answer is copy and pasted from API docs (as embarrassing as that sounds). :-P Luckily it's not my best answer or contribution.
I suspect that even when asking a functional question, adding some
code and talking in terms of APIs will get more votes and responses
than a purely functional question.
How to Handle Expert Users
Moderators should probably have a light touch but not hesitate to make minor adjustments while being conscious of the poster's familiarity with Stack Exchange and intentions. Changing a short "yes you can" answer into a comment might be "heavy handed" if done to a newbie. But what should we do to long-term Tridion forum users and frequent Tridion Stack exchange users? Should experienced "know better?" Dominic has (more than one) of the top posting user accounts on the old forum, btw. ;-)
I guess it depends if you hold those that know better to the same, lower, or higher standards.
But Dominic's nuanced point isn't whether his response should have been a comment (it probably should have been), but whether moderators should do it (and do it quickly). But then in practice that would be Bart-as-a-user telling Dominic to change his simple answer into a simple comment. Is it wrong to do that by taking the action as an admin? I don't know, I feel it should be okay but from personal experience just votes to close sting, even when I know and agree with them.
Maybe the first mistake was in answering the question...
Bart points out we "can improve a poor answer and get nothing for it or add your own answer and get points for it..." I think there's also an incentive to leave a bad question alone, especially if we have a good answer for it ("no, don't close this yet, I have a good answer!").
I think the proper response to a closed-ended (yes/no) question such as "can I
create users with the Core Service?" would be something like: "Welcome
to Tridion Stack Exchange. Yes, of course you can. What have you tried?" as a
comment or two.
I'm guilty of answering "bad" questions, though.
The concern, Dominic, that "Shortly afterwards, someone else gives exactly my answer, adding a trivial example, and reaps all the glory." In your deleted answer you did get the asker's gratitude as a comment. But neither (as of now) got an accepted answer. The point tart in you should respond with "well, please accept my answer then!" (moot with the "answer" now gone, though). ;-)
On sarcastic take-away is when in doubt, add code! :-)