I strongly disagree. I wouldn't call Rails legacy, but _mature_. And the recent adoption of Webpack(er) certainly brings new life to the framework, allowing me to write ES6 JS with a lot of convention over configuration.

I love starting new projects in Rails, and don't feel the need to look anywhere else: it handles everything for me in a very nice and battle tested way, and I'm always one Google / StackOverflow question away from finding out exactly how to achieve my goals quickly.