The truth is you need almost everything to do push and pull. Just as pull alone does "forks" inefficiently, push alone does "joins" inefficiently.
People shy away from this conclusion because doing everything both ways is quite hard and requires fancier abstractions to make nice than people are familiar with.
This is exactly why data patterns like Observables (https://github.com/tc39/proposal-observable) and ReactiveX (http://reactivex.io/) are so powerful. You can design your interface to be subjective to both. :)