
The rationale for disabling this is: 1) systemd timers are better; 2) it gets rid of one usually unnecessary process, which makes containers more light-weight. Note that cron is still enabled if services.cron.systemCronJobs is non-empty, so this only matters if you have no declarative cron jobs but do have user cron jobs.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.