Publish the interface and committing to keep them stable is exactly what the systemd team did. Of course internal interface are not stable and sparsely documen

Publish the interface and committing to keep them stable is exactly what the systemd team did. Of course internal interface are not stable and sparsely documented, but they are just that, internal. Reimplementors should only bother about the public interfaces. Note that udev does not use systemd internal interfaces and happily runs on non-systemd systems. Journald can be disabled if you don't want it, or you want to run it on non-systemd?