The reasons are no mystery. As a sibling to your comment said, many programs have been written as if X was going to exist forever, with direct calls to X all o

The reasons are no mystery. As a sibling to your comment said, many programs have been written as if X was going to exist forever, with direct calls to X all over the place. Plus X is mature with a million accumulated bug-fixes, so naturally it takes time to produce a reasonable contender.