One more aspect: when you have a complex database schema, GraphQL can give you a nice API for free (see Hasura). The other option is to spend resources on a separate "backend-for-frontend" API.
I would not consider tightly coupled frontend and backend as an API at all, because there you don't have an interface for programming applications (more than one).
Yes indeed. I prefer my APIs to be decoupled when working on a larger project. Somewhere near the end I mention building GraphQL schema or code-first. Including generators for GraphQL schemas like StepZen
As a "lifelong" GraphQL user I'm curious about your thoughts