It is a terrible idea organizationally. It puts backend devs at the whims of often hype train and CV driven development of frontend devs. What often happens is, that complexity is moved from the frontend to the backend. But that complexity is not necessarily implicit, but often self inflicted accidental complexity by choices in frontend. The backend API should facilitate getting the required data to render pages and perform required operations to interact with that data. Everything else is optimization that one may or may not need.