I noticed recently while reviewing that several questions with close votes also had accepted answers. What is the point of voting to close a question with an accepted answer?
What is the point of voting to close ( or closing in general ) a question with an accepted answer?
Whether a question is on-topic has nothing to do with the presence of answers, whether those are upvoted or not. We close questions for various reasons (see the tour and help/on-topic). As Masked Man said I don't see why the presence of an answer changes anything about those reasons.
Ideally questions would be closed quickly and in a perfect world people wouldn't answer questions that are obviously off-topic and destined to be closed without further edits or clarification. But there are people on every site in the network that answer questions when they should know better and you find them at all reputation levels. Very often these answers are incredibly easy ("We can't tell you this" or "Ask a lawyer"), get some upvotes and then prevent the question from ever being deleted.
The most direct advantage of closing questions when they have answers is that once the question is closed and it along with any answers have a negative score, trusted users can actually vote to delete them. Deletions become effectively impossible when questions are kept open for too long as you then typically do have answers coming.
I would turn the question around and ask, "Why should the presence of an accepted answer be of any relevance in deciding to close a question?"
We close questions when the 5 members of the community decide that the question is not a good fit for the site. The fact that the OP found an answer anyway doesn't lower the bar for the question.