You can use systemd with the classic logging tools by installing and enabling their respective service if you prefer. This will forward all messages to them. You even get a more comprehensive log than before systemd as the latter will even forward the messages that were sent before the logging service was started.

Edit: similarly for cron, you can still use the classic tools. I see their appeal in ease of configuration. Though in my opinion, systemd timers are more powerful and better integrated (don't ask me why, I made that assessment years ago) so I accept that increased complexity.

For logs, I actually prefer the systemd journal though