The fact that a question can be answered does not mean that it cannot be closed, otherwise we would just have to leave everything open on the premise that someone somewhere might at any second leave a reasonably valid answer.
I'm going to disagree about the significance of the top voted answer in this case; WRT it being a "short paragraph" that short paragraph is a direct quote from the page it links to, and that's all that saves it from being a marginal link only answer.
I recently wrote extensively about this general topic here, so if you are interested in a more in depth explanation of my own perspective (which is pretty orthodox), there you go. To the list of things SE purposefully is not, mentioned there (a discussion forum, an IRC site, a wiki, a blog, a mail list, etc.), I will add a search engine, which is often, and clearly in this case, what reasonable link only answers are responses to. This does not mean that we are not these things because those things are stupid and pointless. We are not those things because there are plenty of resources filling those fine niches already, and there is no need for us trying to be all things to all people. If you look down the list of questions on any given day, it might be observed that the new questions we get which are not closed do not always receive the attention they might deserve -- point being, we are not overflowing with resources on the A side of the Q&A economy, as I explain in that other post.
Note the first clause on the tool tip of the downvote button is "This question does not show any research effort" and indeed, that question does not show any research effort. It is also worth noting:
That question was closed within 24 hours by receiving five close votes, something which is almost unheard of here.
One of those close votes was from the same user who posted the top rated answer.
Finally, I'll provide a link and quote of my own, to the What types of questions should I avoid asking? page in the help center:
You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page.
Your questions should be reasonably scoped. If you can imagine an entire book that answers your question, you’re asking too much.