If you are running your own webserver even a static simple site has required maintenance. You need to keep the server and OS patched. So adding a letsencrypt cron job is not any worse than configuring something like Debian's unattended-upgrades.
But I don't think most site owners should be doing even that much. They should just pay for static hosting, which is cheap and ensures somebody else will keep the server, os, and cert all safe.
But I don't think most site owners should be doing even that much. They should just pay for static hosting, which is cheap and ensures somebody else will keep the server, os, and cert all safe.