https://emacs.stackexchange.com/help/privileges/close-questions says:
It takes 5 close votes to reach the closing threshold. The exception to this is duplicate questions, which can be marked as a duplicate with a single vote from a user who has earned a gold tag badge in one of that question's current tags (unless that user participated in editing that question's tags).
The same page on S.O. says 3 votes rather than 5, so apparently there is a difference in the config here, which could always be reviewed if the setting isn't working as well as it could in practice.
The exception for duplicates is noteworthy, because outside of E.S.
almost any Emacs questions are tagged emacs, and so the users who
have answered a lot of Emacs questions on S.O. can usually close
other Emacs questions as duplicates by themselves.
Here on E.S. the tags are spread much thinner, for obvious reasons. You being rather active in making corrections when people have used tags inappropriately is probably working against you for this particular purpose :)