I really dislike that systemctl subcommands do not respect the accepted standard of `command subcommand -h`. For example, try `git branch -h` or `systemctl start -h`. The latter won't give any useful information.
The man page does not help either. `man git branch` opens the manual of the `git-branch` binary, so only the relevant options are shown. `man systemctl start` will show the man of the entire systemctl command, which is a bit unwieldy.
`journalctl` is the same: it both does paging through the logs, but also manages rotating or vacuuming the logs. Why not have two commands?