As indicated in your comment, out of the 32 questions tagged with the webmaster tag, it appears that several mistakenly used this in replace of the google-webmaster-tools tag, which is now a synonym of the google-search-console tag.
That's likely because Google often references "webmasters" in its documentation and URLs, even after the re-branding to Google Search Console. We still get questions that reference it as "Google Webmasters"...
The tag does appear to be redundant, so I'm going to review the questions that have used it and edit them to use Google Search Console instead in the cases where that seemed to be intended - then I'll remove the webmaster tag.
It should be noted however that users with a reputation over 300 can still create the tag again. If it's not used again within 6 months, it will automatically be deleted from the system.
All of the questions tagged with webmaster were edited and re-tagged accordingly. In doing so, it became apparent that there was a correlation between being hastily written and using this tag...
Tags which don't have any questions will automatically be deleted within a 24-hour period. So if a tag was added that obviously has little value for the site, and ins't a commonly used synonym of another tag, it can simply be removed from tagged questions and it will be deleted by the system (without a moderator's assistance).
If there's any question about a tag's usefulness however, especially if it's been used by several other questions, it's always a good idea to bring it up for discussion on the Meta site like this first.
The webmaster tag was indeed killed-off by the system at 03:00 UTC after removing it from all questions. RIP.