I find that if I'm having to deeply nest result hierarchies into my REST payload I probably haven't spent a lot of time thinking about how the API I am building will be consumed. Usually designing my endpoints to align more closely with the concepts consumers of the API expect prevents the need to nest a lot of data. You may have to break your endpoints away from your data structures somewhat and reorganize your API into the logical structures that more closely represent the way interactions are performed in your software.

That's not to discount GraphQL, because I think it clearly has it's use cases, especially at Facebook size.