Note that not every journald/journalctl is created equal. It's easy to end up with logs written on one computer that journalctl on another computer can't read, even if the latter is a newer version, depending on which settings each one was compiled with (which is mostly a distro question.)
All right, then that seems like a reasonable objection to the format, not simply "It's a binary format." gzip files created anywhere can be read by any version of gzip.
A standalone (and cross-platform) journalctl file reader seems like a useful thing to have around and not a terribly difficult thing for someone to build.
