let's be fair, Pipes can do a little bit more then pure functions. E.g. the async pipe which lets someone directly use Observables in the view is really helpful

let's be fair, Pipes can do a little bit more then pure functions. E.g. the async pipe which lets someone directly use Observables in the view is really helpful. And a simple function in combination with Observable.map() or Promise.then() won't bringt that functionality to React (you need to write lifecycle hooks or mixins, and in the end it would look similar to your construct.