My 2 cents, at Facebook scale there is no framework that will handle all the "boring stuff".
I am not even sure what you even mean by boring stuff. But if you are like some of the devs I have worked with I have heard over and over why do we have to write all this CRUD for forms and dashboards etc.
There are no shortcuts, and no frameworks that just magically solve all the problems without introducing tradeoffs.
You can stretch Rails a whole lot these days -- so much so that by the time Rails is the bottleneck, you can probably afford to hire primo engineers to refactor to better tools.
I would however build the real-time chat system with Elixir and Phoenix. Just knock that out and not worry about chat performance for a very long time.
So I would build the main app with Rails. And the chat system with Elixir.
I am not even sure what you even mean by boring stuff. But if you are like some of the devs I have worked with I have heard over and over why do we have to write all this CRUD for forms and dashboards etc.
There are no shortcuts, and no frameworks that just magically solve all the problems without introducing tradeoffs.