With great effort. That’s kind of my point though. It’s when you are changing the design from the originally understood “these are the ways to extend and add”,

With great effort. That’s kind of my point though. It’s when you are changing the design from the originally understood “these are the ways to extend and add”, to a new paradigm, that you should be expending great effort. In such a code base, it quickly becomes understood that if changes are required to “framework Doom” in order to achieve a new feature, the time budget will need to be large. It’s built in tech-debt prevention.