This question recently popped to the top of the active question queue. I spent some time reading the question, added some comments, and then realized that the last visible activity was a month ago.
To make sure I wasn't losing my mind, I returned to the Active queue to see if the question really had appeared there. I saw that the activity was generated by the Community user:
Since no edits appear on the question or answers, what is Community doing that causes the question to be considered "active?" For what it's worth, I have noticed the same behavior a handful of times before today.