Frontend engineers don't have to be isolated in their own world. If they can learn JS and the craziness of JS frameworks they can learn Ruby or Python or whatever. Way too much complexity is added to web app development because of this idea that backend and frontend are two completely different worlds.
They usually already know JS? My point is about not isolating dev teams into front/back islands from a systems, product, and team management perspective.
Adding a separate JS frontend is a good way to double your costs and dev time. There's few situations that demand such heavy JS but people follow trends like sheep. And I say that as a frontend engineer who wrote JS/TS for a decade.
