Although it's hard to make answers into tutorials, I think sometimes it can be helpful for future readers to add some text to help the OP parse the code they posted. Mathematica code can be quite hard to read, and I do think that if you already decided to answer because the fix seems easy to you, then it can't hurt to add some verbal comments.
In fact, the system sometimes flags answers containing only code and no explanations as "low-quality posts." That's not the case in your linked answer since you also included a screen shot (and engaged in the comment discussion).
So basically there is some initial decision when you look at posts like this: is it worth an answer? If no, then close it. If yes, then try to make it useful to others who are looking to learn, by taking your best guess as to what the central point is that should be explained, and frame the answer that way.
In these cases it's also common that the OP comes back with multiple follow-up questions, but at least one can reign in the discussion a little if the answer already contains some guidance. If I suspect that the OP doesn't know what they want at all, then I usually don't answer in the first place.