You have one example of a project not providing an API, however there are tons of other GNU projects which do. Furthermore the GCC decision is well documented

You have one example of a project not providing an API, however there are tons of other GNU projects which do. Furthermore the GCC decision is well documented in mailing list posts, have you ever seen anyone involved in GPG development claim that they won't allow a library/frontend split for fear of someone writing a proprietary frontend?