When the PR #13928 (one-way bindings) was discussed, the shallow watching (using $watchCollection) wasn't implemented as it wasn't clear what the use case is. Seems like I've found a use case.

Suppose we have a component:

app.component('myList', {
  template: '...',
  bindings: { items: '<' }
});

and it's used like this:

<my-list items="items|orderBy:'title'"></my-list>

Can you see what's going on here? The orderBy filter returns a new array every time it's called, so we get $rootScope:infdig. Plunker.

Changing the type of the binding to =* makes it work.