To clarify, I'm not thinking of code/libraries written by a huge company, more about open source code that has been scaled far beyond your deployment size by so

To clarify, I'm not thinking of code/libraries written by a huge company, more about open source code that has been scaled far beyond your deployment size by someone/anyone else. Also, if you're using some feature that isn't regularly exercised (like your Swift protobuf example), it's probably doesn't have the variety of use to be covered by Hyrum's Law (see https://www.hyrumslaw.com https://www.hyrumslaw.com ), which is definitely a different aspect of the Ubiquity criteria.