I am wondering if the rewriting rule applies to AdWords and search, I mean they probably would get very upset if their cashcow stops working, all of a sudden.
But both, search and adwords, have been rewritten multiple times since their launch.
You can have a look at the papers created by Jeff Dean (1) and Sanjay Ghemawat (2) which mention some of the new concepts/technologies/features used in those products.
1: https://ai.google/research/people/jeff 2: https://ai.google/research/people/SanjayGhemawat
https://developers.google.com/google-ads/api/docs/start
Disclosure: I co-author the Python client library and have written a few of the docs on the site listed above.