If you change the output of "ls", you know everything that uses ls will break and you can bump a major version. But if you change e.g. the date format to include a timezone (visible when -l is specified), does such a change really warrant a major version bump? It's just a minor change but it might still break things. Or maybe if you refactor some stuff in curl, the curl-dev package might suddenly be incompatible with something that depended on it.
If you change the output of "ls", you know everything that uses ls will break and you can bump a major version. But if you change e.g. the date format to include a timezone (visible when -l is specified), does such a change really warrant a major version bump? It's just a minor change but it might still break things. Or maybe if you refactor some stuff in curl, the curl-dev package might suddenly be incompatible with something that depended on it.