Very basic (La)TeX questions are a tricky area as at least to some extent many of them could be covered by the concept 'read a manual'. There should be a space for asking good basic questions, certainly when they are phrased such that the question is clear, self-contained and likely to help future user. More problematic are basic questions where that's not the case: the one raised here certainly isn't a great question.
As we know, 'off topic' is one of the reasons the 'Powers' give us to close questions and is intended not only to cover out-and-out off-topic posts but also stuff not answered 'by convention'. In some areas, such as typos and bug reports, we have had the discussion and reached a consensus that at present 'off topic' is the most appropriate way to handle them. However, that I know of we've not had a general discussion about 'basic' questions and how to deal with them.
Closing questions isn't necessarily a negative thing: the idea for example of marking duplicates is to avoid repeated effort in answering questions (likely over time to lead to poorer answers) while pointing the questioner to useful resources and hopefully aiding anyone searching in the future. Similarly, closing as 'off topic' or 'too broad' doesn't mean that there is not a valid discussion to be had about something: it means that the format here isn't suited to such a discussion. Thus the issue is at least in part is what reason(s) are appropriate for closing (some) general questions and how should this be phrased/commented to make the action helpful.
One issue here is that not all 'general' questions are the same. Some as I say I think are very solid useful posts which deserve good upvotes and good answers. On the other hand, some questions we see are poorly formulated and difficult to assign to one specific issue. Those might be too broad or might be off topic. On the other hand, questions which we do have clear answers for (hopefully attached to clear questions) should be marked as duplicates: that applies generally. I suspect as such there is an element of 'use your judgement' here. I think what is important is that any closing has appropriate comments, that you are clear that any dupe does really answer the question, and that the questioner is given time to address comments before a closure happens.
One thing to bear in mind is that having answers doesn't mean a question should not be closed. In his answer Percusse suggests that as the 'lead' question here has been answered that closing is not required. While there is some truth in the idea that closing is about site stats, it's also meant to be as I say not a universally negative step. It's quite possible for example for a dupe to be spotted after an answer is given: the question can still be a duplicate in those circumstances.
Bottom line: I'd probably have gone for 'duplicate' here.
One issue here that has been mentioned is that when there are a mix of close votes for different reason the system only marks with one reason. That's not something we can control locally, but is I always think rather odd. Perhaps one to raise on the main meta site.
