Agree that I should not just stick Rc everywhere. The use of borrow checkers makes a lot of sense at a macro scale, i.e: libraries, APIs. But, I’m just wondering the justification for using Rc in a smaller scope, say inside my own implementation of a trait. If I am to provide external APIs then yes, sticking Rc everywhere would not be a good idea ergonomically.
One high level problem with learning Rust is that a lot of the patterns we use to work with the borrow checker are pretty non-obvious. (Things like using indexes instead of references, and avoiding methods that keep &self borrowed.) To the extend that Rc and Arc let you avoid learning those patterns, I agree with folks who say not to use them too much. But if you know how you might solve something without Rc, and you want to try it with Rc anyway to see how it feels, that's totally reasonable.
