Maybe an answer from an unexpected person, but with my participation here on Magento SE, I have also got interested in the Stack Exchange platform in general and have read about lots of things involved in it's system.
The thing (privilege) you are wielding is called a "dupe hammer" and indeed it comes with any gold tag badge and gives you the privilege of single handedly close ("hammer") questions as duplicate ("dupe") that have been tagged with that tag.
You are not the first with questions on the why, what and how of dupe hammering. If you'd look at all the questions on SE Meta or SO Meta, you'll see that it comes with great responsibility ;): closing by accident, discussions about it's power etc...
I think it is great that people who have shown proven expertise in a certain topic get additional moderator like privileges. Raphael, I wish you great fun, good luck and above all much wisdom in using your "dupe hammer" :P