This is very true! In practice I have seen that it is exceedingly difficult to write the GraphQL "sinks" (I don't recall the exact term) that can intelligently handle things like batching and understanding things like pre filtering, where one service in the composed call could and should be performed first to limit the result set. YMMV, in my experience it can be simpler to be more explicit about these things, especially when in "true" BFF the client team is also responsible for their immediate backend, which can give them that flexibility, at the cost, perhaps, of more boilerplate.
