Going to assume you're talking frontend? Otherwise you'd be claiming most Spring, Django, Rails, Angular, <enter common backend framework> codebases are a nightmare to work in. While there are many good application architectures that don't fit into the MVC pattern (or introduce additional layers, e.g. - auth), separating DB ops (M) from business logic (C) and endpoint handlers (V) has always been rather maintainable/testable in my experience.