I don’t think the issue lies in using the same language to write the client & server. IME projects become brittle & hard to refactor when you use a full stack framework because you wind up writing a ton of controller code or a sprawling service layer to support different features for each page. This isn’t exclusive to using a framework, I’ve done the same thing with API endpoints in the past.

Making a general purpose API as if it were its own product seems to lead to better, more sustainable outcomes.