This is a great sum-up of a point I often find myself making a lot when explaining GraphQL. GraphQL is only capable of doing exactly what the server-side developer lets it. Order-by is a really great example. We can sort by only the things that make sense to sort by, and often at Facebook we're sorting by heuristics like "sort my friends by how likely I am to send them a message" when loading the friends in a typeahead for chat, and this idea of "message send likelihood" is not exposed as a field.
