Overuse of "Rc+RefCell/Arc+Mutex" IS something of an antipattern though. In C programming you try and avoid doing too much of that kind of thing as you can get

Overuse of "Rc+RefCell/Arc+Mutex" IS something of an antipattern though. In C programming you try and avoid doing too much of that kind of thing as you can get stuck in "undefined behavior" whereas in Rust you'll instead end up coding yourself into a circular dependency or some other construct that will never compile. So I agree that you should avoid using them other than where needed in Rust.