A database can afford to fsync to ensure consistency, and
they've been heavily tested to ensure it works properly.
And even then its still possible that the file becomes corrupt, if the OS, or the disk lies about fsync:
https://www.sqlite.org/howtocorrupt.html
Has journald been tested on how well it copes with sudden reboots, kernel panics, powerloss, etc.?
When something goes wrong you usually want to be able to still read your logs to figure out what happened, and you may not even be able to boot the system properly.
Databases have been around a lot longer than systemd, so I assume they are better tested than journald in this regard.
I don't use systemd - because Debian doesn't use it (yet) - so it was rather a question for those who do use systemd.
I'm not saying that I'd be happy to have a database as journald backend, I'd be just less concerned.
Has journald been tested on how well it copes with sudden reboots, kernel panics, powerloss, etc.?
When something goes wrong you usually want to be able to still read your logs to figure out what happened, and you may not even be able to boot the system properly.