Unenforced privacy is a Bad Idea for (shared) libraries that may be upgraded independently of whatever uses them. It means that any internal change becomes a br

Unenforced privacy is a Bad Idea for (shared) libraries that may be upgraded independently of whatever uses them. It means that any internal change becomes a breaking change, and when some application stops working after a library upgrade it is your fault regardless that you told the application developers "don't do that" (the users don't know or care that you said that, they only know that upgrading your library broke their stuff).