It used to be that cron(8) was always installed. Now it's optional.

But some packages still assume cron is always installed, and therefore they
need to have their RPM's updated to add a "Requires: cron" line.

Examples:

    $ rpm -qf /etc/cron.daily/{mdadm,packagekit-background.cron}
/etc/sysstat/sysstat.cron
    mdadm-4.0-lp150.8.6.1.x86_64
    PackageKit-1.1.10-lp150.11.1.x86_64
    sysstat-12.0.2-lp150.16.1.x86_64
    $ rpm -qR mdadm PackageKit sysstat | grep cron | wc -l
    0

So "Requires: cron" needs to be added to at least mdadm, PackageKit, and
sysstat.

I'm sure there are others...