I don't know what you're contradicting because I never said the corruption gets fixed. I said it's skipped over. Specifically what happens is upon detection of corruption, journald stops writing to the corrupt journal file, creates a new journal file, and new entries go there. The utility for reading the journal files, journalctl, can also detect this corruption and will skip over detected corruption and continue on.

I have no idea what version of systemd Ubuntu 16.04 has, but in systemd-233 I'm not seeing aforementioned problems with -b switch and corrupt journal files.