In 99% of cases, users do not need to set manual tags, but this functionality is very easily susceptible to vandalism and is very difficult to rollback (https://www.mediawiki.org/wiki/Special:Log/tag). Those who set up wikis may not know about this functionality in principle. It seems to me that these rights should be given by default only to bots and administrators.
As you can see many wikis have requested that these rights be removed from regular users: https://phabricator.wikimedia.org/search/query/rGhue4JXkFhy/#R
Current not-default permissions:
|Wiki|Groups|Future permissions
|cswiki|bot, sysop|-
|commonswiki|bot, sysop|-
|enwiki|bot, sysop|-
|frwiki|bot, autopatrolled|autopatrolled
|hrwiki|bot, sysop|-
|itwiki|bot, botadmin, sysop|botadmin
|jawiki|bot, abusefilter, sysop, interface-admin|abusefilter, interface-admin
|metawiki|bot, sysop|-
|ruwiki|bot, sysop|-
|simplewiki|bot, sysop|-
|trwiki|sysop|-bot
|wikidata|sysop|-bot
|simplewiki|bot, sysop|-