They're significantly more time-consuming, for the developer, to work with. Think of using something like a lambda to start a thread: You have to explicitly cl

They're significantly more time-consuming, for the developer, to work with. Think of using something like a lambda to start a thread: You have to explicitly clone your Rc<Whatever> into another variable, and then use the second variable in your lambda. The compiler won't implicitly clone your RC<Whatever> for you. IMO, it's one of the biggest drawbacks in Rust.