The idea of a rewrite is a newbie mistake. It is almost always wrong. https://www.joelonsoftware.com/2000/04/06/things-you-should-never-do-part-i/
MacOS wasn’t rewritten, it was ported. It’s now bigger than before.
Linux has grown from 170k lines of code back when I used it to handle dns for 10k customers to 40 million lines today. It has never been “completely rewritten” . Is Linux a failure?
Imo MS has a need to keep Windows convoluted so as to stay one step ahead of cloners like Wine.








The OP said the Intel to Apple Silicon transition. That was after OS X. Nor was the earlier Mac OS a rewrite but adding a different GUI to Next step and calling it Mac OS X.