Especially when a user cannot delete their own question.
Broadly speaking, closing a question is not usually an instantaneous thing (and rightly so) so it is entirely possible that, during the time a question accumulates the required number of votes to close, other users upvote or even answer the question. In fact I would not be surprised if à faire fraction closed questions had some votes (up or down) and/or some answers (also with votes).
One perfectly legitimate reason to close an upvoted question with an upvoted answer is duplication. Failure to close will eventually generate huge amounts of repetition and will make the site difficult to search.
Closing a question should not be a race, and neither should up- or downvoting. As a result, I do not think that up-voted questions with answers should be immune from closure.
Of course it is also my experience that many posters fail to properly search the site for duplicates or near duplicates, or fail to understand that direct homework questions are off-topic. There are many other examples where the natural delay built in the closing mechanism is likely longer than the time it takes to cast an upvote or write a simple answer.