User blog comment:DaNASCAT/Technical Update: January 6, 2016/@comment-24473195-20160107161235/@comment-24473195-20160107181739

UserTags is a bloated script, and might probably contain security exploits. Nobody has really reviewed its code and it hasn't been updated for 2 years. It is also very complicated for the average user to use, one small mistake while editing and the script stops working, in addition to mixing configuration with the regular code. Lastly, each time you edit it you need to ask staff to review the edits, and considering that mediawiki doesn't validate javascript scripts before submission it is entirely possible that they may reject your changes after more than 2 days waiting.

Basically, it needs a serious rewrite.