You’re saying rather than use a system tool that does the exact thing that you want you should bodge together a cron job that accomplishes your goal but doesn’t actually do what you want.
Like say you want to stop the docker service for some reason? systemctl stop docker will do that. Then your cron job will restart it. That’s not the desired outcome. You want the service running IF the service SHOULD be running. Which is a different thing than “always running”. And its’ exactly what you get for free with systemd without any silly custom BS.