I think it's fair to compare with the classic Dropbox vs ftp argument.
It takes some configuring to make sure crown sends emails to the right place - and without the email going straight to spam. Sure you can setup filters, etc. But that's manual work. Not to mention of you'd rather have it text you, send a message to slack etc.
Also cron can't alert you if you accidentally removed the cron job, the host is down, host loses its connection etc.
We have certain cron jobs that if they failed we could be losing thousands of dollars an hour.
Of course they're tested, and you're right they've worked fine for a looooong time.
But I don't care if they "normally work fine", I need to know immediately if it didn't run for any reason. We self hosted a cron monitor, it was free and only took less then a day to add and have fully integrated, including text message and MS teams notifications.
It takes some configuring to make sure crown sends emails to the right place - and without the email going straight to spam. Sure you can setup filters, etc. But that's manual work. Not to mention of you'd rather have it text you, send a message to slack etc.
Also cron can't alert you if you accidentally removed the cron job, the host is down, host loses its connection etc.