When you use something like Apollo + a graphQL backend it makes client-side code considerably easier to deal with. Think of how much front-end code is simply fetching data, storing it locally, and then creating components to render that data. With Apollo, you use declarative graphQL strings to state what data you need to render a view, and then it handles all the fetching/retry/cache/subscription logic for you. You're able to iterate quicker because you have less CRUD code to deal with.

Other benefits are that you don't need to write multiple endpoints to serve condensed responses, since the client declares exactly what data it needs in the request. So a mobile client that only needs a fraction of the data of a web client can get back exactly what it needs, and there's no need for the backend to create separate REST endpoints or params for managing that. It's part of the spec.