Agree on .init. Tend to disagree on $0, especially in one line functions like maps, filters, etc.

The subscript usage as shown is bad. That said, it can be used to add dictionary-style access to caches, repositories, and so on.

The delegate extension example is legitimate, from my perspective.

Agree property wrappers should not be abused, but biggest problem in doing something similar to what's shown is that you inevitably get to a point where you'd want to nest them... and you can't.