Facebook is a large geek shop; not how the vast majority of enterprises work or can work for that matter.
Enterprise cares predominantly about hireability, and Javascript has been the only language for the web for decades. Everyone who even tangentially has a brush with web technologies knows it, and if your company has a frontend team you already have people at your company who know Javascript well.
I predict Javascript will continue to see growing use serverside, at least until the point ten years from now when WebAssembly is mature enough that people can develop for the frontend as well as the backend in any language.