If you just log to stderr, you must have some other system hanging around to read that output and put it in the system log files for you. syslog doesn't do that, but systemd does.

Such systems have been available on Linux-based operating systems since the middle 1990s. It's not a new systemd thing by a long chalk.

* http://jdebp.uk./FGA/daemontools-family.html#Logging

Of course, I didn't say otherwise.