There are two groups that can unilaterally close a question:
Users with a gold badge for a tag on the question can close it as a duplicate. (dnd-5e gold badge holders, in this case.) This is called the dupe hammer.
That is absolutely intended and correct. The same people also can unilaterally reopen questions, with wielders of the dupe ...
See here: New onboarding for review queues
From the question:
We are also showing a popover to users who earned access to review queues in the past, but have never done a review or haven't reviewed in the last 30 days. This popover is only appearing for the next 90 days. The goal is to engage users who may not have interacted with the queues since we made ...
From meta.se: Increase close vote weight for gold tag badge holders
The rules are:
You can instantly close as a duplicate any question that was originally asked with a tag you have a gold badge for.
You can instantly reopen any question closed as a duplicate that was originally asked with a tag you have a gold badge for.
You can only close or reopen a ...