Actually, your sample "solution" is (was?) also a much used pattern in Julia - especially before we had such a powerful broadcast implementation.
So in Julia there is no need either, since it is already implemented much better in Base. I think you're overlooking the actual point of my challenge: it's not that we need a broadcast package, but that a lot of other scientific libraries will need to use similar patterns, to write new packages with new algorithms!
The point is also, that I can go into the Julia repository, and without a lot of time & effort, can improve the current implementation of our broadcast - because it is not that much code and pretty easy to follow.
So, an equivalent in your example would be, if you can quickly implement something like repa or folds in a similar minimal example like my Julia implementation.
If you don't like the details of my challenge, feel free to make a minimal folds implementation from scratch, and show me that the result is fast and composable ;)