It take longer to adopt and learn RoR than ES6. Both have their owns strength but Javascript and Python skills can be apply to any organizations, RoR is quite limited.
There are mature, production-ready server-side web app frameworks with relational database adapters in literally every mainstream programming language (and many of the obscure ones too) except for JavaScript. I didn't say you have to do Ruby on Rails. If you prefer Python, then you can just use Django, it is more or less equivalent to Rails.
