I would say that with Rust you can be "more" productive by deploying apps that requires less maintenance as for example Ruby or JS app, also a pain with JS/Ruby

I would say that with Rust you can be "more" productive by deploying apps that requires less maintenance as for example Ruby or JS app, also a pain with JS/Ruby is updating dependencies, that's a very scary thing to do if you are far behind, while with Rust you can update and instantly see where your code broke. But I do agree that with Rails you can have quickly a more functional app, but that will be sooner or later not true anymore.