I think your second paragraph hits the nail on the head. What's the point of writing an architecture that's extensible if it requires the user to know all of yo

I think your second paragraph hits the nail on the head. What's the point of writing an architecture that's extensible if it requires the user to know all of your code in-depth to use it? Now, if the code was packaged as an API with very good documentation, then this might be a moot point. In my personal experience, this has rarely been the case.