Then consider this your warning
Seriously, if there's anything you'd miss on your Mac, backup. I've had two primary harddrives fail on me spontaneously in about 5 years. Not too bad considering how much I use my computers but my backups saved me both times.
Yeah, I'm usually a Windows user so I'm not used to things messing up like this.
But you're right, when using MacOS you really want a backup.