RESTful interfaces and headless implementations have been on the minds of developers and less technical people alike. This has been the state for a number of years now and frankly the REST hype is getting a bit long in the tooth.
While REST is a technology with merits, the problem is that REST is only used as a baseline technology definition in most cases. There is no specific definition on what a REST API is, that's why many resort to calling them RESTful - to describe that they sort of fulfil the definition. But without knowing exactly what is meant by REST, it's hard to say.
Next enters GraphQL, a new alternative for REST APIs. Coming from the Facebook open source initiatives, it's a very robust technology already used by millions. Unlike REST, GraphQL is an explicit standard that defines how things should be done.
Using GraphQL enables developers to learn a common language instead of heavy investment into application specific REST APIs, like the one in Drupal 8. In the future it is better to decouple using a headless CMS that uses GraphQL, rather than traditional REST.