The benefits of keyword arguments without all of the extra code:
some_method(a:, b:, c:, d: d + 4)
Now we can quickly see only d is being modified, allowing us to more clearly see the intent of the code, while also getting all of the benefits of keyword arguments around name checks, value checks, and more easily understood methods.
I see this being the highest value add.
Looking forward to seeing how I like this in Ruby land.