GraphQL has been public since June 2015, and there's been at least one solution to the n+1 problem (Dataloader) since September 2015. If you were using pure REST endpoints (just resources, no nesting/traversal) this is the exact problem you'd be punting over to the client to solve -- all that GraphQL is doing here is moving it back onto the server. The actual amount of work is the same, you just get faster response times.
Most implementations of GraphQL I've seen in different languages provide some variation on the Dataloader pattern. I'll fully concede it can be a hassle to set it up correctly, but it works.