I mean an example of why this new language feature -- the ability to implicitly treat a keypath as a function -- is useful. (The last example in your link show

I mean an example of why this new language feature -- the ability to implicitly treat a keypath as a function -- is useful. (The last example in your link shows using a keypath to specify a sort criteria. That's a nice use of keypaths, but isn't helped by this new feature.)