It’s less about notebooks, but more about SDLC practices. Notebooks may encourage writing throwaway code, but if you split code correctly, then you can do unit testing, write modular code, etc. And ability to use “arbitrary files” as Python packages exists for quite a while, so you can get best of both worlds - quick iteration, plus ability to package your code as a wheel and distribute
P.S. here is a simple example of unit testing: https://github.com/alexott/databricks-nutter-repos-demo - I wrote it more than three years ago.