You're right, they're definitely many cases where incorporating any calls to external resources would be the wrong call and where hitting a local copy of a db would be the best solution.
An API such as this exists would be a great choice where you need to modify content on the frontend. In which case you'd benefit from the availability of 10 endpoints around the world from which the API is available to provide the lowest latency to your users.
I get what you mean. However from the use cases I've seen often whatever processing needs to be done eg. showing a banner ad to users from a particular state or redirecting to a country specific version of a site can be handled from the user's browser.
Even if you're not hosting the country specific site in that region your user will still save time on making the call to our endpoint local to them.
An API such as this exists would be a great choice where you need to modify content on the frontend. In which case you'd benefit from the availability of 10 endpoints around the world from which the API is available to provide the lowest latency to your users.