I have rewritten personal projects from scratch because I can better structure it the second time around, but I'm only talking about a few thousand lines of code... MacOS is MILLIONS of lines of code, and has never been re-written as a whole. There are frameworks in MacOS that were originally made for NextStep and OS9 still hanging around. Things get updated and reworked, but rarely rewritten in their entirety. That would be a completely unsustainable way to maintain something as complex as an OS!Those are words coming from former Google and Microsoft Devs now professors. Unless they’re lying to us completely or have weird coding practices, that what I’m preparing for in the job market.
I always start over mostly fresh in every major update to my projects.