By this logic every language should have C-style headers. There's nothing to prevent me from creating a bloated API/interface with or without the framework forcing me to declare it external to the class, in interfaces, headers or otherwise.

In Eclipse it's as simple as using the refactor tool to 'pull up interface' from any God Class of my choosing.

Neither language nor framework can force a coder to apply the Single Responsibility Principle. Coders can be willy-nilly with or without interfaces.