<p><a href="https://meta.stackexchange.com/q/165933/256777">Here is the relevant Meta.SE thread</a>:</p>

<blockquote>
  <p>The search results include only answered questions (per the usual SO definition of "answered", where the question must have an accepted or up-voted answer). ... Moderators can override this last restriction if necessary.</p>
  
  <p>The rationale here is that it can be fairly hard to discern whether or not an unanswered question is actually a duplicate, and even when it is closing doesn't really accomplish very much. When searching for a "canonical" answer in particular, duplicates without answers (or with bad answers) are just noise in the results. </p>
</blockquote>

<p>This decision has not been uncontroversial - the original post is now at -16, and <a href="https://meta.stackexchange.com/q/165928/256777">here is a highly-upvoted thread advocating that questions without answers should be valid duplicates</a>.</p>
