In #2981793-11: Allow metatag configuration to be disabled → @grayle wrote:
Added warning when disabling Global default that this will disable all Metatags, as there's an early return in the code and I didn't feel like changing that part was warranted in this issue.
Disable the global metatag. miss the warning and get confused
Either remove the ability completely to disable the global metatag or change the code to make it work with global disabled.
If you don't want metatags uninstall the module. In my opinion you should be able to disable the global metatag defaults and only add metatags to entity types you want to.
Active
2.1
Code
In fact the whole way the global metatag object is loading and then changed using \Drupal\metatag\Entity\MetatagDefaults::overwriteTags is quite interesting. This will end up changing the cached config object in memory (if we turned on memory caching for metatag defaults config entities).
I think we should try to tidy all of this up and allow the metatags system to work when the global defaults are disabled.