Every day one-time user accounts by spambots with random unfilterable names (e.g. WarnerArida7421; MoisesMcCasland; LuzOfd704934; LulaGow839899; GeraldineP17; EvaShort134) are created on otherwise low traffic wikis. These accounts never get used, especially with the Abuse Filter extension blocking the spam. On a wiki with only a handful of active editors there are instead thousands of dormant user accounts. Please add an option for user accounts that have never done an edit to be auto-removed.
This is a feature that is unlikely to be developed into Core MediaWiki, as there is many areas in MediaWiki that can user account without onwiki visible usage (eg: Watchlists, User Preferences).
To combat the spam accounts, have a look at https://www.mediawiki.org/wiki/Extension:UserMerge to delete accounts and https://www.mediawiki.org/wiki/Manual:Combating_spam has tips on combatting spam issues
One example might be restricting account creations then using a solution such as https://www.mediawiki.org/wiki/Extension:ConfirmAccount
Wiki's hosted on a wiki farm might not have the option to use extension:UserMerge
So this is a request to bundle UserMerge into core? Cf.
The wiki is hosted on a wiki farm which uses CentralAuth. To prevent the global accounts being affected only sysadmins of the wiki farm can rename, merge and delete. Local sysadmins can't access Extension:UserMerge.
That might be an argument to fix the wikifarm's setup instead of a reason to implement more functionality in MediaWiki Core and increase code complexity and maintenance costs to fix an unclear problem... Which problem do these unused accounts create exactly, in which workflows?